Layered grid collimator system

Abstract

A layered grid collimator system is disclosed, in one embodiment, the collimator system may include: a hollow connection base layer fixedly connected to a radiotherapy device; the grid collimator frame is connected with the connecting base layer and is used for mounting a grid collimator; the grid collimator is composed of a plurality of layers of grid collimation bodies, and each layer of grid collimation body is installed on the grid collimation body frame; and the layered grid collimation body driving mechanism is configured to drive the layered grid collimation body to move. Through the structural design, the dose distribution can be adjusted as required, and the processing difficulty and cost of the collimator are reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of radiotherapy, in particular to a layered grid collimator used for space-fractionated radiotherapy. Background Art

[0002] The traditional method of radiotherapy is to try to deposit a relatively uniform dose throughout the tumor to kill the tumor. Spatially Fractionated Radiation Therapy (SFRT), introduced by Kohler in 1909, uses a grid collimator or other technology to form a discontinuous high-dose distribution at certain intervals within the tumor, while keeping the normal tissue around the tumor at a lower dose to avoid related toxicity. A large number of clinical studies have shown that for tumors that are poorly responsive to conventional radiotherapy (such as large tumors, radiation-resistant tumors, and recurrent tumors), SFRT's control of tumors and toxicity to normal tissues are better than expected.

[0003] The key to SFRT is to use smaller beamlets to form a discontinuous high-dose distribution at certain intervals inside the tumor. According to the size of the beamlet, SFRT can be divided into grid therapy, lattice therapy, mini beam therapy and micro beam therapy. Currently, grid and lattice therapy have been used clinically, while mini beam and micro beam therapy are still in the research stage. The main differences between the four technologies lie in the beamlet size and the beamlet spacing distance (the beamlet spacing distance is generally several times the beamlet size). The beamlet size of grid and lattice therapy is in the centimeter level, the beamlets of mini beam therapy are reduced to millimeters to hundreds of microns, and the beamlets of micro beam therapy are further reduced to tens of microns.

[0004] Currently, a commonly used method for implementing beamlet irradiation is to use a multi-leaf collimator (MLC) or a grid collimator to collimate a large beam into smaller beamlets or a beamlet matrix.

[0005] There are several advantages of MLC-based SFRT: ① The existing linear accelerator treatment heads are basically pre-installed with MLC, and MLC-based SFRT is easy to use in various radiotherapy centers; ② MLC has been accurately modeled in the treatment planning system, and accurate dose calculation can be easily achieved; ③ The size of the small field and the distance between the fields can be arbitrarily changed; ④ With the multi-angle irradiation of the linear accelerator, three-dimensional SFRT can be achieved. However, the main problems of MLC-based SFRT are: ① Compared with the grid collimator, the MLC leaf size is larger, and it is difficult to form an aperture of similar size to the grid collimator; ② The influence of leakage between MLC leaves on the shielding area; ③ The mechanical restrictions on the movement of the accelerator jaw and MLC increase the difficulty and time of treatment; ④ Compared with the grid collimator, the peak-to-valley ratio (i.e., the ratio of high dose (peak dose) to low dose (valley dose) inside the tumor) of MLC-based SFRT is lower.

[0006] SFRT based on grid collimators is still the main implementation method of SFRT because it can achieve a larger peak-to-valley ratio. However, the traditional grid collimators have the following main problems: ① It needs to undergo additional fine processing. For small beams (MiniBeam) and microbeams (MicroBeam), the current processing technology is difficult to achieve the aperture requirements of millimeters or even microns; ② The aperture, spacing and peak-to-valley ratio of the grid cannot be changed arbitrarily, so it needs to be customized one by one according to needs during clinical use, which is time-consuming and economically costly and inconvenient for clinical use; ③ The grid collimator needs to be precisely assembled with the head of the radiotherapy equipment to ensure the accuracy of the grid collimator position. The assembly of each newly customized grid collimator takes a lot of time. Utility Model Content

[0007] In order to solve at least one of the above-mentioned defects existing in the prior art, the utility model provides a grid collimator system with a spatially segmented radiotherapy layered structure, which can reduce the processing difficulty of the grid collimator, effectively realize the on-demand adjustment of the dose, and is flexible in use.

[0008] According to one aspect of the utility model, a layered grid collimator system is provided, the collimator system comprising: a hollow connecting base layer, which is fixedly connected to a radiotherapy device; a grid collimator frame, which is connected to the connecting base layer and is used to install a grid collimator; a grid collimator, which is composed of a plurality of layered grid collimators, each layered grid collimator being installed on the grid collimator frame; and a layered grid collimator driving mechanism, which is configured to drive the layered grid collimators to move.

[0009] In some embodiments, the connection base layer is provided with a sliding mechanism outside the hollow range, and the grid collimator frame is connected to the connection base layer via the sliding mechanism.

[0010] In some embodiments, the collimator system may further include: a grid collimator frame driving mechanism configured to drive the grid collimator frame to translate along a predetermined direction.

[0011] In some embodiments, the grid collimator frame has lateral sliding rails and sliders for each layered grid collimator at the installation height of each layered grid collimator.

[0012] In some embodiments, each of the layered grid collimators is provided with grid holes of predetermined apertures at predetermined intervals.

[0013] In some embodiments, the predetermined spacing may be in the range of millimeters to centimeters; and the predetermined aperture may be in the range of sub-millimeters to centimeters.

[0014] In some embodiments, the grid holes may be in various shapes such as regular polygon, rectangle, circle or ellipse.

[0015] In some embodiments, the layered grid collimator driving mechanism includes a plurality of sub-driving mechanisms corresponding to the layers of grid collimators, and the layers of grid collimators are driven by their own sub-driving mechanisms to independently move in a plane perpendicular to the beam of the radiotherapy device.

[0016] In some embodiments, the layered grid collimator driving mechanism includes a driving motor and a transmission mechanism, and the transmission mechanism is configured to convert the rotation of the driving motor into a translational or rotational movement of each layered grid collimator.

[0017] In the specific implementation process, once the layered grid collimation system of the embodiment of the utility model is assembled on the treatment head of the radiotherapy equipment, the different layered grid collimators in the collimator can be driven by a high-precision motor to move (for example, translate or rotate). Through the relative movement between the different layered grid collimators in the collimator, a grid with continuously adjustable aperture from the maximum aperture to the minimum aperture can be formed while keeping the grid spacing unchanged, thereby avoiding the time and economic cost required for customizing and assembling grid collimators with different apertures. Secondly, the layered grid collimator of the embodiment of the utility model can realize continuous adjustment of the grid spacing by overall movement and batch irradiation, thereby adjusting the dose and distribution of the beam passing through the collimator. Thirdly, the shielding thickness of the grid collimator is an important factor affecting the peak-to-valley ratio. The layered grid collimator of the embodiment of the utility model can adjust the equivalent shielding thickness of the entire collimator system by moving each layered grid collimator out of or into the irradiation field, thereby adjusting the peak-to-valley ratio formed by the entire collimator system. Fourthly, the layered grid collimator of the embodiment of the utility model can statically or dynamically modulate the dose distribution within the grid aperture through the relative movement between different layered grid collimators, so as to form a dose distribution that better meets clinical needs.

[0018] It can be seen that compared with the traditional physical grid collimator, the layered grid collimator system provided by the embodiment of the utility model does not need to add complex software and hardware equipment, and can realize the on-demand adjustment of the grid aperture, interval, peak-to-valley ratio and dose distribution in the grid hole on the basis of realizing the functions of the traditional grid collimator, and is more flexible to use. At the same time, since there is no need to process small-aperture grids, the processing difficulty of the grid collimator is reduced.

[0019] Certain aspects, advantages and novel features of the present invention have been described above for the purpose of summarizing the present application. It should be understood that, according to any particular embodiment of the present invention, not all of these advantages must be achieved. Therefore, the present invention can be implemented or implemented in a manner that achieves or optimizes one advantage or a group of advantages taught herein without having to achieve other advantages taught or illustrated herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] By describing the utility model embodiments in more detail in conjunction with the accompanying drawings, the above and other purposes, features and advantages of the utility model will become more apparent. The accompanying drawings are used to provide a further understanding of the utility model embodiments, and constitute a part of the specification, and are used together with the utility model embodiments to explain the utility model, and do not constitute a limitation of the utility model. In the accompanying drawings, the same reference numerals usually represent the same parts. It should be understood that the size and size of the parts shown in the figures are not necessarily drawn to scale, and they may be different from the embodiments shown here for implementation. In addition, some embodiments can be combined with any suitable combination of features from two or more drawings.

[0021] Figure 1 This is a schematic diagram of the overall assembly structure of various components of a layered grid collimator according to an embodiment of the present application;

[0022] Figure 2 A bottom view of a structure connecting a base layer according to an embodiment of the present application;

[0023] Figure 3 is a schematic structural diagram of a layered grid collimator frame according to an embodiment of the present application;

[0024] Figure 4 It is a schematic diagram of a sliding guide rail and a driving mechanism of a layered grid collimator frame according to an embodiment of the present application;

[0025] Figure 5A-5B Schematic diagram of the structure of a layered grid collimator according to an embodiment of the present application (taking two layers as an example)

[0026] Figure 6A-6B A schematic diagram of a layered grid collimator according to an embodiment of the present application forming a small aperture grid by interlacing;

[0027] Figure 7 Schematic diagram of dose distribution in a water phantom of an initial aperture grid of a layered grid collimator and a small aperture grid formed by interlacing according to an embodiment of the present application;

[0028] Figures 8A-8B A schematic diagram of a layered grid collimator according to an embodiment of the present application realizing grid spacing adjustment through overall translation illumination;

[0029] Figures 9A-9B Schematic diagram of dose distribution in the phantom before and after the grid collimator is translated according to an embodiment of the present application (left) and a schematic diagram of the final dose distribution formed in the phantom after two irradiations (right);

[0030] Figures 10A-10B Schematic diagram of adjusting the equivalent thickness and peak-to-valley ratio of the layered grid collimator by moving out the upper collimator;

[0031] Fig.11 A schematic diagram of dose distribution in a phantom before and after a layered grid collimator according to an embodiment of the present application is moved out of an upper collimation body;

[0032] Fig.12 It is a schematic diagram of a layered grid collimator according to an embodiment of the present application forming sub-grids through relative movement, thereby adjusting the dose distribution within the aperture. DETAILED DESCRIPTION

[0033] Below, the exemplary embodiments according to the present utility model will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application, and it should be understood that the present application is not limited to the exemplary embodiments described here.

[0034] In order to solve the problems existing in the prior art, the present application embodiment proposes a layered grid collimator system for spatial fractionation radiotherapy. Figure 1 Figure 2 shows a schematic diagram of the three-dimensional structure of the overall assembly of the components of the collimator system. Figure 1 As shown, the collimator system may include: a connecting base layer 100, which may be fixedly connected to a treatment head of a radiotherapy device, the connecting base layer 100 having a hollow portion so that a beam emitted from the treatment head passes through the hollow portion; a layered grid collimator frame 200, which is coupled to the connecting base layer 100 and is used to install a grid collimator composed of layered grid collimators; a grid collimator 300, which has a layered structure, for example, composed of a plurality of layered grid collimators, wherein each layer of grid collimators is installed on the layered grid collimator frame 200; and a driving mechanism, which may include, for example, a layered grid collimator driving mechanism 410, which is configured to drive each layer of grid collimators of the grid collimator 300 to move.

[0035] In some embodiments, the driving structure may further include a layered grid collimator frame driving structure 420, which may drive the layered grid collimator frame 200 to move along a predetermined direction and drive the grid collimator 300 to move as a whole. Figure 1 A sliding mechanism such as a sliding track is installed on the bottom surface of the basic connection layer 100. The layered grid collimator frame 200 can be connected to the connecting basic layer 100 through the sliding mechanism and can slide along the track. Its specific structure will be described below.

[0036] In some embodiments, the layered grid collimator system of the present application embodiment can be installed inside or below the treatment head of the radiotherapy device, and its maximum irradiation range is substantially the same as the maximum field range of the existing radiotherapy device. The existing collimation system (such as jaws and MLC) of the treatment head of the radiotherapy device is used to conform the irradiation target area, which can effectively reduce the dose received by normal tissues around the target area.

[0037] Figure 2 FIG. 2 shows a bottom view of the structure of the connection base layer 100 according to an embodiment of the present application. Figure 2 As shown, the connection base layer 100 may include a base connection plate 101, which is generally circular. A square opening 102 is provided in the center of the base connection plate 101, and the size of the opening is not less than the projected area of ​​the maximum field of the radiotherapy equipment at the installation height of the base connection plate, so as to avoid attenuation of the beam generated by the radiotherapy equipment. A fixing mechanism such as a positioning screw (not shown) is provided on the upper surface of the base connection plate 101, which is convenient for fixed connection with the treatment head of the radiotherapy equipment and can rotate with the frame and treatment head of the radiotherapy equipment. Two main sliding guide rails or tracks 103 and 104, for example, parallel to the main axis (X axis or Y axis) of the radiotherapy equipment are arranged outside the hollow range of the lower surface of the base connection plate 101 (i.e., outside the central square opening), and multiple (for example, two) sliders are slidably installed on each guide rail. In one embodiment, the layered grid collimator frame 200 can be fixed on the slider in the sliding guide rail of the connection base layer, so that it can be driven by a driving motor to perform translational movement along the direction of the main axis of the radiotherapy equipment. In another embodiment, as described below, the layered grid collimator frame 200 can be connected to the primary slide rails via secondary slide rails, which can increase the freedom of movement of the layered grid collimator frame 200.

[0038] Reference Figure 2 The sliders 105, 106, 107, and 108 may be rectangular parallelepiped structures, and the upper surfaces thereof are embedded in the main sliding rails 103 or 104, so that the sliders 105, 106, 107, and 108 may slide along the main sliding rail direction on the main sliding rails 103 or 104. Figure 1, a circular hole 121 with an inner thread may be provided at the center of the slider rectangular parallelepiped parallel to the direction of the main sliding track, through which a driving screw with an outer thread may pass and mesh with the outer thread of the driving screw. The two ends of the driving screw are fixed on the driving piles 111 and 120, and can rotate around the axis of the driving screw under the drive of a driving mechanism (for example, a driving motor 112) coaxially fixed to the screw on the other side of the driving pile 111. When the driving motor 112 rotates, it can drive the screw to rotate, and the outer thread of the screw meshes with the inner thread of the center hole of the driving slider, converting the rotational motion of the driving screw into the translational motion of the driving slider on the main sliding tracks 103 and 104. The direction and distance of the translation along the main sliding track are determined by the direction, speed and time of the rotation of the driving motor, and can be accurately controlled by a control device such as a computer. Preferably, the minimum distance between the two pairs of driving piles (i.e., the minimum effective stroke of the two driving screws) is not less than the grid hole spacing d of the grid collimator, which will be described later.

[0039] In one embodiment, the lower surfaces of the sliders 105 and 107 and 106 and 108 are rigidly connected to a section of a secondary sliding guide rail or track 109 and 110, respectively, so that the main sliding track (103 and 104) and the secondary sliding track (109 and 110) form a "#" shaped structure. Similar to the main sliding track, the secondary sliding track is also provided with sliders (113, 114, 115 and 116) with the same structure and function and corresponding drive motors 117, drive piles 118 and 119. The lower surfaces of the sliders 113, 114, 115 and 116 are rigidly fixedly connected to the fixed frame back plate 201 of the layered grid collimator fixed frame 200. Therefore, by rotating the drive motors 112 and 117, the layered grid collimator fixed frame can be driven to translate a required distance along the main axis and / or secondary axis direction of the radiotherapy device.

[0040] The sliding, transmission mechanism and working principle of the embodiment of the present application are introduced above through guide rails, screws, etc. It should be pointed out that the present application is not limited to this. For example, transmission mechanisms such as gears and belts can also be used to achieve the rotational movement of the (disc-shaped) collimator, which is also within the protection scope of the present application.

[0041] Figure 3 FIG. 2 shows a schematic diagram of a three-dimensional structure of a layered grid collimator frame 200 according to an embodiment of the present application. Figure 3As shown, the layered grid collimator frame 200 for mounting a fixed collimator is composed of a fixed frame back plate 201 and four corner columns (202, 203, 204 and 205). As described above, the fixed frame back plate 201 can be rigidly connected to the slider on the primary or secondary sliding track, and can be specifically a rectangular rigid flat plate, the long axis of which is along the main axis direction (X axis or Y axis) of the radiotherapy device. A square hole 206 is opened in the center of the fixed frame back plate 201, which is similar to the opening 102 connected to the base layer 100. The size of the hole 206 is not less than the projected area of ​​the maximum field of the radiotherapy device at the installation height of the fixed frame back plate to avoid attenuation of the radiation beam. The four corner columns (202, 203, 204 and 205) are rigidly fixed vertically on the four corners of the fixed frame back plate 201 for mounting the layered grid collimator, and the height of the corner column can be not less than the sum of the heights of the layered grid collimator and its guide rails to be installed.

[0042] Figure 4 A schematic diagram of a layered grid collimator frame according to an embodiment of the present application is shown, which specifically shows components such as sliding and driving mechanisms. In one embodiment, a sliding mechanism for each layered grid collimator is provided on the side of the layered grid collimator frame 200 at the installation height of each layered grid collimator, such as a lateral sliding track and a slider. Figure 4 As shown, the layered grid collimator frame 200 is provided with lateral main sliding tracks corresponding to each layered grid collimator between two diagonal columns (i.e., 202 and 203 and 204 and 205) along the main axis direction of the radiotherapy device. Taking a two-layer grid collimator as an example, two layers of sliding tracks are installed at different heights on the layered grid collimator frame 200, for example, sliding tracks 206 and 207 are used for the layered grid collimators of the upper layer, and sliding tracks 208 and 209 are used for the layered grid collimators of the lower layer. Preferably, the length of the main sliding track can at least ensure that each layered grid collimator can be completely moved out of the radiation field along the main sliding track, thereby facilitating the adjustment of the radiation dose.

[0043] Each main sliding track is embedded with 2 sliders, that is, the upper and lower sliding tracks can be equipped with 4 sliders, refer to Figure 4 The two sliding rails of the lower layer are respectively embedded with sliders 221, 223 and 222, 224, and the two sliding rails of the upper layer are also embedded with four sliders (only slider 213 is shown in the figure), and the structure and function of each slider are the same as those in the above reference. Figure 2The sliders described are the same and will not be described in detail. A secondary sliding track (225 and 226) is installed laterally between two opposite sliders (for example, 223 and 224) on the two main sliding tracks of each layer. The secondary sliding track is perpendicular to the main sliding track to form a "#" shaped structure. Each layered grid collimator is fixedly connected to the side of the slider on the secondary sliding track on the corresponding layer through the side (vertical surface). The use of side fixing can minimize the installation height of the sliding track and the auxiliary drive mechanism in the vertical direction, reduce the gap between each layered grid collimator, and improve the structural compactness of the entire layered grid collimator.

[0044] In order to drive the layered grid collimator of the collimator, a driving mechanism may be provided on the side of the slider. In one embodiment, the layered grid collimator driving mechanism may include a plurality of sub-driving mechanisms corresponding to each layer of the grid collimator, and each layer of the grid collimator may independently move in a plane perpendicular to the beam of the radiotherapy device under the drive of its own sub-driving mechanism. For example, the same driving structure (driving motor, circular hole with inner thread, driving screw with outer thread, driving pile) and driving method as the movement of the layered grid collimator frame 200 may be adopted, and each layered grid collimator may independently translate on its own main sliding track and secondary sliding track. For example, the layered grid collimator driving mechanism includes a driving motor and a transmission mechanism, and the transmission mechanism may be configured to convert the rotation of the driving motor into the translational or rotational movement of each grid collimator. Since each layered grid collimator is equipped with an independent driving mechanism, in which the driving motor can rotate at a certain speed and a certain angle under the control of a computer or other controller, and then the transmission mechanism can convert the rotation of the driving motor into the translation or rotation movement of each grid collimator, each layered grid collimator can independently translate any distance or rotate any angle with high precision under the control of the computer. Therefore, the relative movement of each grid collimator can be either translation or rotation; at the same time, the relative movement of each grid collimator can be either isotropic or anisotropic.

[0045] It should be pointed out that since each layered grid collimator does not need to be moved out of the radiation field along the secondary sliding track, there is no specific limitation on the length of the secondary sliding track. The minimum distance between the corresponding driving piles of the sliders on the secondary sliding track of each layer (i.e., the minimum effective stroke of the two driving screws) only needs to be no less than the grid hole spacing d of the grid collimator.

[0046] Figure 5A-5B Schematic diagram of the structure of a layered grid collimator according to an embodiment of the present application. This embodiment shows that the collimator includes two layers of grid collimators, layered grid collimator 301 and layered grid collimator 302. The present application is not limited thereto, and the number of layers of the layered grid collimator includes but is not limited to 2 layers, and can also be divided into more layers as needed. Figure 5AAs shown, each layer of grid collimators 301 and 302 can be made of (rounded) rectangular high-density materials (e.g., heavy metal) of the same size and thickness (H). Figure 5B As shown, the surface perpendicular to the beam direction (XY plane) is a (rounded) square. Grid holes may be provided on each layer of the grid collimator at a predetermined interval, for example, square grid holes with the same aperture (Φ) and the same interval (d) are provided along the beam direction. Since different layers of collimators are located on planes at different distances from the source, for the convenience of description, these dimensions refer to their dimensions on the reference plane of the radiotherapy equipment. In one embodiment, the diagonal of the square is along the main axis direction (X-axis and Y-axis) of the radiotherapy equipment. When each layer of the grid collimator is at zero position, the center lines of the corresponding grid holes on each layer of the grid collimator coincide.

[0047] Although FIG. 5 shows grid holes of a specific shape, it is understood that the grid holes of each grid collimator can be designed to any shape as needed, including but not limited to regular polygons (e.g., squares, regular triangles, regular hexagons), rectangles, circles, ellipses, etc. The major and minor axes of each grid hole can be parallel to the main axis direction of the radiotherapy device, or can be at any angle to the main axis direction of the radiotherapy device. The size (aperture Φ) of the grid holes on each layer of the grid collimator can also be designed to any size as needed, such as a range from several centimeters to several millimeters. In addition, the spacing (d) between the grid holes on each layer of the grid collimator can also be designed to any size as needed, such as a range from several centimeters to several millimeters.

[0048] Through the structural design of the embodiment of the present application, the irradiation dose can be adjusted as needed. In one embodiment, when the collimator system is in the initial state, each layer of the grid collimator can be set at the initial position so that the corresponding grid holes of each layer of the grid collimator are aligned with each other to form a whole. When the collimator system is used for collimation operation, the layered grid collimator driving mechanism can be used to drive each layer of the grid collimator to move to achieve the expected irradiation dose distribution.

[0049] In one embodiment, the layered grid collimator driving mechanism can be used to drive each layer of the grid collimator to perform relative movement to adjust the aperture of the effective grid that is not attenuated by each layer of the grid collimator. When the layered grid collimator moves relative to each other under the action of the driving mechanism, the corresponding grids on each layer of the grid collimator will be staggered, thereby reducing the aperture of the effective grid that is completely unattenuated by each layer of the grid collimator. Generally speaking, the greater the relative movement of the layered grid collimator, the greater the staggering of the corresponding grids on each layer of the grid collimator, and the smaller the effective grid aperture. When the corresponding grids on each layer of the grid collimator move to the grid interval of other layers of the grid collimator, the effective grid aperture is reduced to 0. In this way, the collimator of the embodiment of the present application realizes continuous adjustment from the maximum grid aperture to the minimum grid aperture, which facilitates the clinical selection of a suitable aperture, avoids the cost of processing a set of grid collimators from large to small, and also avoids the technical difficulties of processing a small-aperture grid collimator.

[0050] In one embodiment, the layered grid collimator frame driving mechanism or each layered grid collimator driving mechanism can be used to drive the layered grid collimator frame to move, so as to drive the grid collimator to translate as a whole, thereby adjusting the spatial distribution of the dose. Specifically, for a grid collimator with a grid hole spacing of d, the grid beam spacing can be adjusted by a batch irradiation mode. The first irradiation at the initial position can form a grid beam with an interval of d. When the grid beam spacing required clinically is d', the irradiation can be implemented by translating each layer of the grid collimator as a whole by a distance of d / n (n=d / d', n is a positive integer) in the direction of the grid spacing. Similarly, the grid collimator is translated as a whole n times to implement batch irradiation, and finally a grid beam with a grid spacing of d / n can be formed, thereby achieving the purpose of adjusting the grid spacing according to clinical needs.

[0051] In one embodiment, a layered grid collimator driving mechanism is used to drive the grid collimators of a partial layer to move so that the grid collimators of the partial layer are moved out of the radiation field range, thereby adjusting the effective thickness of the collimator. For example, the required thickness of the collimator that needs to be placed in the irradiation range can be determined based on the peak-to-valley ratio required clinically, and then a portion of the upper grid collimator or a portion of the lower grid collimator or a portion of the grid collimator in the interval is removed from the radiation field range, and the effective thickness of the remaining grid collimators in the radiation field range is made the same as the predetermined required thickness. Preferably, starting from the uppermost layered grid collimator, the corresponding layered grid collimators can be moved out of the radiation range one by one through each layered grid collimator driving structure until the equivalent thickness of the remaining lower layered grid collimator is the same as the required thickness calculated based on the peak-to-valley ratio required clinically. Compared with the method of adjusting the effective thickness of the entire grid collimation system by removing the lower collimator and retaining the upper collimator, the method of removing the upper collimator and retaining the lower collimator is more beneficial to reducing the geometric penumbra of the sub-beam.

[0052] In one embodiment, when a specific dose distribution is clinically required in the grid holes, the relative movement of each layered grid collimator can be used to form the required sub-grids, and the dose distribution in the grid holes can be adjusted by static or dynamic intensity modulation of independent collimators to meet clinical requirements.

[0053] For ease of understanding of the present utility model, refer to FIG. Fig.12 The working process of the layered grid collimator of the present invention is exemplarily described. It can be understood that these specific embodiments do not constitute a limitation on the embodiments of the present invention.

[0054] Example 1

[0055] Figure 6A-6B is a schematic diagram of a layered grid collimator according to an embodiment of the present application forming a small aperture grid by interlacing, Figure 7 This is a schematic diagram of the dose distribution in a water phantom of the initial aperture grid of the layered grid collimator and the small aperture grid formed by interlacing according to an embodiment of the present application. Through this embodiment, the aperture of the grid collimator can be adjusted as needed.

[0056] Reference Fig. 6A When each layer of grid collimator is at the initial position (zero position), the center lines of the corresponding grid holes on each layer of grid collimator coincide, forming a grid collimator with an equivalent thickness of 2H, an aperture diagonal length of Φ, and a grid hole spacing of d. The radiation beam emitted by the treatment head of the radiotherapy device can be irradiated on the simulated target area of ​​the phantom after passing through the collimator. For example, the dose distribution formed in the phantom with a surface perpendicular to the beam direction can be as follows: Figure 7 Shown as solid line.

[0057] When a smaller beam is needed clinically, the driving mechanism of each layer of collimator can be used to drive each layer of collimator to move backward by a predetermined distance D / 2 (D<Φ), thereby causing the corresponding grids of the upper and lower grid collimators to be misaligned, and finally forming a square grid hole with an aperture diagonal of Φ-D (this aperture defines the area of ​​the effective grid that is not attenuated by each layer of grid collimator), an equivalent thickness of H, and a spacing of d (such as Figure 6B At this time, the dose distribution formed by the beam emitted by the treatment head in the phantom whose surface is perpendicular to the beam direction can be shown as follows: Figure 7 As shown by the dotted line. It can be seen that the adjusted dose intensity is lower than the original dose intensity. By adjusting the predetermined distance of the back movement, the grid aperture of the grid collimator can be continuously adjusted from 0 to Φ using the embodiment of the utility model, and accordingly, the dose intensity can be continuously adjusted.

[0058] Example 2

[0059] Figures 8A-8BSchematic diagram of adjusting the grid spacing by overall translational illumination of the layered grid collimator according to an embodiment of the present application. Figures 9A-9B Schematic diagram of dose distribution in the phantom before and after translation of the grid collimator according to an embodiment of the present application (left) and a schematic diagram of the final dose distribution formed in the phantom after two irradiations (right). Through this embodiment, the grid hole spacing of the grid collimator can be adjusted as needed.

[0060] Reference Fig. 8A Combined with the previous description, when each layer of the grid collimator moves back and forth by D / 2 (D<Φ), a grid collimator with an equivalent thickness of H, an aperture diagonal length of Φ-D, and a spacing of d will be formed. After the treatment head irradiates a specific dose, the dose distribution formed in the phantom with a surface perpendicular to the beam direction can be as follows: Fig.9A As shown by the solid line in . Figure 8B As shown in the figure, the grid collimator is translated by the driving mechanism of the layered grid collimator frame by a distance d / 2 along the hole spacing direction. After irradiating the same dose, the dose distribution formed in the phantom whose surface is perpendicular to the beam direction will be as follows: Fig.9A After two irradiations, the final dose distribution in the phantom is as shown in Fig. 9B As shown, this movement is equivalent to halving the grid hole spacing of the grid collimator.

[0061] This embodiment is illustrated by moving the collimator a specific distance, but it is obviously understandable that the grid collimator can be translated in any direction according to clinical needs using the driving mechanism of the layered grid collimator frame as a whole, and the translation distance can also be any distance less than the initial hole spacing (d) (for example, d / n, n is a positive integer). That is, the grid hole spacing of the grid collimator can be continuously adjusted in the two-dimensional direction within the range of 0 to d using this embodiment.

[0062] Example 3

[0063] Figures 10A-10B Schematic diagram of adjusting the equivalent thickness and peak-to-valley ratio of the layered grid collimator by moving the upper collimator. Fig.11 This is a schematic diagram of the dose distribution in the phantom before and after the layered grid collimator is moved out of the upper collimation body according to an embodiment of the present application. Through this embodiment, the peak-to-valley ratio of the grid holes of the grid collimator can be adjusted as needed.

[0064] Reference Fig. 10AWhen the grid collimators of each layer are at zero position, the center lines of the corresponding grid holes on each layer of the grid collimators coincide, forming a grid collimator with an equivalent thickness of 2H, an aperture diagonal length of Φ, and a spacing of d. The beam emitted by the treatment head of the radiotherapy device can be irradiated on the simulated target area of ​​the phantom after passing through the collimator. The dose distribution formed in the phantom whose surface is perpendicular to the beam direction can be shown as Fig.11 When a lower peak-to-trough ratio is clinically required, such as Fig. 10B As shown in the figure, the driving mechanism of the first grid collimator can be used to move the first grid collimator out of the radiation field along the main sliding track, thereby forming a square grid hole with an aperture diagonal of Φ, an equivalent thickness of H, and a spacing of d. Due to the reduction of the shielding thickness outside the aperture, the field dose increases and the peak-to-valley ratio decreases. The dose distribution formed by the beam in the phantom with a surface perpendicular to the beam direction will be as follows Fig.11 Shown by dotted line.

[0065] This embodiment is illustrated by taking the collimator including two layers of layered grid collimators as an example. Obviously, for a multi-layered grid collimator, in order to achieve the purpose of adjusting the peak-to-valley ratio, the equivalent thickness of the collimator that needs to be retained within the radiation field and the number of layers of the layered grid collimators that need to be moved out of the radiation field (including but not limited to 1 layer) can be calculated according to clinical needs. The more layered grid collimators the grid collimator includes, the more peak-to-valley ratios can be achieved through this embodiment, and the more flexible the adjustment. As described above, moving part of the grid collimators out of the radiation field can be done by moving them out layer by layer from the first layer (top layer) downwards, or by moving them out layer by layer from the last layer (bottom layer), or by moving them out layer by layer from one layer to another as needed. Preferably, moving them out layer by layer from the first layer downwards helps to increase the distance from the lower surface of the final collimator to the radiation source, and helps to reduce the geometric penumbra of the beam.

[0066] Example 4

[0067] Fig.12 This is a schematic diagram of a layered grid collimator according to an embodiment of the present application that forms sub-grids through relative movement, thereby adjusting the dose distribution within the aperture. Through this embodiment, on-demand modulation of the dose within the grid holes of the grid collimator can be achieved.

[0068] Reference Fig.12 In the upper left figure, combined with the previous description, when each layer of the grid collimator is at zero position, the center lines of the corresponding grid holes on each layer of the grid collimator coincide, forming a grid collimator with an equivalent thickness of 2H, an aperture of 5×5 (unit length), and a spacing of d. The beam emitted by the treatment head of the radiotherapy device can be irradiated on the simulated target area of ​​the phantom after passing through the collimator. The dose distribution formed in the phantom whose surface is perpendicular to the beam direction can be shown as follows Figure 7 , 11When a specific dose distribution is required within this aperture clinically, the driving mechanism of each layered grid collimator can be used to drive each layered grid collimator to move relative to each other once or multiple times to form the required sub-grids, each of which defines the corresponding irradiation sub-beam, for example, 3×3 ( Fig.12 Middle picture above) and 1×1( Fig.12 By superimposing the irradiation results of each sub-beam, the intensity / dose distribution required for clinical use is modulated within this aperture range ( Fig.12 below).

[0069] It is understood that the order of driving the layered grid collimator to move and using the treatment head for irradiation is not limited in this embodiment. For example, the on-demand modulation of the dose distribution in the grid aperture can be achieved by using the relative movement of each layer of the grid collimator to form a sub-beam and then irradiate and superimpose to achieve static modulation, or by the relative movement of each layer of the grid collimator during the beam output process to achieve dynamic modulation.

[0070] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.

[0071] As used herein, words such as "include," "comprises," "have," and the like are open ended words that mean "including but not limited to," and are used interchangeably therewith. The words "or" and "and" as used herein mean the words "and / or," and are used interchangeably therewith, unless the context clearly indicates otherwise. The word "such as," as used herein, means the phrase "such as but not limited to," and is used interchangeably therewith.

[0072] The above is only the preferred arrangement disclosed in this application and is not intended to limit this application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of this application should be included in the protection scope of this application.

Claims

1. A layered grid collimator system, characterized in that: The collimator system comprises: A hollow connection base layer fixedly connected to the radiotherapy device; A grid collimator frame connected to the connection base layer and used for mounting a grid collimator; A grid collimator, which is composed of a plurality of layered grid collimators, each layered grid collimator is mounted on the grid collimator frame; and The layered grid collimator driving mechanism is configured to drive the layered grid collimator to move.

2. The layered grid collimator system of claim 1, wherein: The connection base layer is provided with a sliding mechanism outside the hollow range, and the grid collimator frame is connected to the connection base layer through the sliding mechanism.

3. The layered grid collimator system according to claim 1 or 2, wherein: The collimator system further comprises: The grid collimator frame driving mechanism is configured to drive the grid collimator frame to translate along a predetermined direction.

4. The layered grid collimator system according to claim 1 or 2, wherein: The side surface of the grid collimator frame is provided with a lateral sliding track and a sliding block for each layered grid collimator at the installation height of each layered grid collimator.

5. The layered grid collimator system according to claim 1 or 2, wherein: Each of the layered grid collimators is provided with grid holes of predetermined apertures at predetermined intervals.

6. The layered grid collimator system according to claim 1 or 2, wherein: The layered grid collimator driving mechanism comprises a plurality of sub-driving mechanisms corresponding to the grid collimators of each layer, and the grid collimators of each layer move independently in a plane perpendicular to the beam of the radiotherapy device under the drive of the respective sub-driving mechanisms.

7. The layered grid collimator system of claim 1, wherein: The layered grid collimator driving mechanism comprises a driving motor and a transmission mechanism, wherein the transmission mechanism is configured to convert the rotation of the driving motor into a translational or rotational motion of each layered grid collimator.

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