Grid for forming spatially fractionated x-rays and radiation therapy device having same

Abstract

A grid for forming spatially fractionated X-rays is disclosed. The grid includes an upper surface positioned on the upstream side of an X-ray, a lower surface positioned on the downstream side of an X-ray, and a plurality of elongated holes extending from the upper surface to the lower surface, the holes being radially arranged from the upper surface toward the lower surface.

Description

Grid for forming spatially divided X-rays and a radiation therapy machine having the same

[0001] The present invention relates to a grid and a radiation therapy device having the same, and more specifically, to a grid for forming spatially divided X-rays and a radiation therapy device having the same.

[0002] Medical linear accelerator-based radiation therapy devices are medical devices that treat cancer by irradiating tumors located inside a patient's body with high-energy X-rays generated from a linear accelerator. Generally, high-output electromagnetic energy is used to accelerate an electron beam in a linear accelerator, and the accelerated electron beam collides with an X-ray target such as tungsten, generating X-rays through the bremsstrahlung effect.

[0003] Generally, radiation therapy is performed by irradiating a patient with X-rays generated from a linear accelerator mounted on a rotating gantry, and the X-ray dose is increased to reduce treatment time and enhance treatment efficacy. However, irradiating a patient with high-dose X-rays during radiation therapy can cause radiation toxicity to normal tissues surrounding the tumor.

[0004] Technology for generating spatially split X-rays is being researched to enhance therapeutic efficacy while suppressing radiation toxicity. When spatially split X-rays are used in radiation therapy, the peak X-ray dose can be increased while maintaining the same average X-ray dose used for cancer treatment. Furthermore, since the same immunological treatment is possible even in tumor regions not irradiated with X-rays, the therapeutic effect can be maximized with the same average dose.

[0005] Conventionally, research has been conducted to enhance therapeutic efficacy by placing a perforated metal structure, or grid, in the path through which X-rays generated by a linear accelerator are irradiated to the patient. This structure allows X-rays to pass through only the perforated areas, generating spatially segmented X-rays that are then irradiated to the patient. However, conventional grids cause interference with the X-rays passing through them, resulting in dose loss. In particular, a significant dose difference is observed between X-rays passing through the holes in the central region of the grid and those passing through the holes in the peripheral region. Consequently, the efficient delivery of X-rays intended for treating the tumor area is hindered, thereby adversely affecting the effectiveness of tumor treatment.

[0006] The problem that the present invention aims to solve is to provide a grid of a new structure for forming spatially divided X-rays, and in particular, to provide a grid of a new structure capable of reducing interference with X-rays and a radiation therapy device having the same.

[0007] According to one embodiment of the present invention, a grid for forming a spatially divided X-ray is provided. The grid comprises an upper surface located upstream of the X-ray; a lower surface located downstream of the X-ray; and a plurality of elongated holes extending from the upper surface to the lower surface, wherein the holes are arranged radially from the upper surface toward the lower surface.

[0008] In one embodiment, the lower surface may include a convex surface having a first radius of curvature, and the exits of the holes may be disposed on the convex surface.

[0009] In one embodiment, the upper surface may include a concave surface having a second radius of curvature, and the entrances of the holes may be disposed on the concave surface.

[0010] In one embodiment, the second radius of curvature may be smaller than the first radius of curvature.

[0011] The first radius of curvature and the second radius of curvature may each be the distance from the center of the target where X-rays are generated to the convex surface and the concave surface.

[0012] In one embodiment, the holes may have the same length as each other.

[0013] In one embodiment, the holes may be arranged in a continuous direction from the center of the target where X-rays are generated to the center of the entrance of each hole.

[0014] In one embodiment, the width of the entrance of the holes may be equal to or smaller than the width of the exit of the holes.

[0015] In one embodiment, the inlet width of the holes is smaller than the outlet width of the holes, and the difference between the inlet width and the outlet width may be within ±10% of the product (t·ra) of the radiation angle (ra) of the inlet of the holes and the length (t) of the holes.

[0016] In one embodiment, the difference in radiation doses of X-rays irradiated through the holes may be less than 10% of the maximum radiation dose.

[0017] The cross-sections of the above holes may be circular, elliptical, or polygonal.

[0018] In one embodiment, the grid may be integral. In another embodiment, the grid may include a plurality of detachable modules and may be replaceable on a module-by-module basis.

[0019] In one embodiment, the grid may be fixed. In another embodiment, the grid may be mechanically or electromagnetically rotated or linearly moved, and may dynamically change the spatially divided X-rays according to the change in position.

[0020] According to one embodiment of the present invention, a radiation therapy device comprising a grid for forming spatially divided X-rays is provided. The radiation therapy device comprises an X-ray target that generates X-rays by an electron beam; a collimator that defines an irradiation area of ​​X-rays generated from the X-ray target; and a grid disposed downstream of the collimator, wherein the grid is the grid described above.

[0021] According to embodiments of the present invention, by adopting a grid having holes arranged in a radial direction, interference between X-rays passing through the holes and the grid can be reduced, and accordingly, X-ray dose loss can be reduced and X-rays for tumor treatment can be efficiently delivered.

[0022] FIG. 1 is a schematic perspective view for illustrating a radiation therapy device according to one embodiment of the present invention.

[0023] FIG. 2 is a schematic cross-sectional view illustrating a radiation cancer treatment device and a grid for forming spatially divided X-rays according to one embodiment of the present invention.

[0024] FIG. 3a is a plan view for explaining the upper surface of a grid according to one embodiment of the present invention.

[0025] FIG. 3b is a plan view for explaining the lower surface of a grid according to one embodiment of the present invention.

[0026] FIG. 4a is a schematic cross-sectional view illustrating a hole in a grid according to one embodiment of the present invention.

[0027] FIG. 4b is a schematic cross-sectional view illustrating a hole in a grid according to another embodiment of the present invention.

[0028] Figure 5 is a simulation diagram showing the typical two-dimensional distribution of radiation dose of X-rays passing through a collimator and a grid.

[0029] Figure 6a is a simulation graph showing the radiation dose on a one-dimensional line according to the prior art.

[0030] FIG. 6b is a simulation graph showing the radiation dose on a one-dimensional line according to an embodiment of the present invention.

[0031] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. The embodiments described below are provided as examples to ensure that the concept of the present invention is sufficiently conveyed to those skilled in the art to which the present invention pertains. Accordingly, the present invention is not limited to the embodiments described below and may be embodied in other forms. Throughout the specification, the same reference numerals indicate the same components.

[0032] FIG. 1 is a schematic perspective view for explaining a radiation therapy device (100) according to one embodiment of the present invention.

[0033] Referring to FIG. 1, the radiation therapy device (100) according to the present embodiment may include a gantry (121), a collimator assembly (123), and a patient placement table (125) on which a patient (129) is placed.

[0034] The gantry (121) can rotate around the patient's area of ​​interest. An X-ray generator is placed within the rotatable gantry (121). An electron beam accelerator can be placed within the gantry (121), and the electron beam accelerator can be placed in a horizontal or vertical direction within the gantry (121). If the electron beam accelerator is placed horizontally, the electron beam accelerated in the horizontal direction can be converted to a vertical direction using a bending magnet or the like, and accordingly, the X-ray generated from the X-ray target can be irradiated vertically toward the patient's (129) area of ​​interest. If the electron beam accelerator is placed vertically, the electron beam collides with the X-ray target without a device for converting the direction of the electron beam, and accordingly, the X-ray generated from the X-ray target can be irradiated vertically.

[0035] The patient placement table (125) can move the patient (129) in the horizontal and vertical directions so that the area of ​​interest of the patient (129) requiring radiation therapy is placed in the X-ray irradiation area.

[0036] The collimator assembly (123) is positioned away from the spatially divided X-ray generator and collimates the generated X-rays so that they are irradiated to an area of ​​interest of the patient (129). The collimator assembly (123) may include a collimator (23 in FIG. 2) for defining the irradiation area of ​​the X-rays generated at the target. A grid (25 in FIG. 2) according to embodiments of the present invention is placed between the collimator (23) and the patient (129) to spatially divide the X-rays that have passed through the collimator (23).

[0037] FIG. 2 is a schematic cross-sectional view for illustrating a radiation cancer treatment device and a grid (25) for forming a spatially divided X-ray according to one embodiment of the present invention, and FIG. 3a and FIG. 3b are plan views for illustrating the upper surface (25a) and lower surface (25b) of the grid (25) according to one embodiment of the present invention, respectively.

[0038] First, referring to FIG. 2, an electron beam (EB) emitted from an electron accelerator collides with a target (21) to emit X-rays (Lx). The X-rays (Lx) are initially defined as an irradiation area by a collimator (23), and then pass through the holes (25h) of a grid (24) to form spatially divided X-rays (Lx) within the irradiation area defined by the collimator (23), which are then irradiated to the patient's area of ​​interest. The collimator (23) defines the irradiation area where the X-rays (Lx) are irradiated, and the grid (25) spatially divides the X-rays (Lx) within the irradiation area.

[0039] The collimator (23) blocks X-rays (Lx) traveling to areas outside the irradiation area and allows X-rays (Lx) traveling to the irradiation area to pass through. The X-rays (Lx) that pass through the collimator (23) travel in a radial direction according to the opening width of the collimator (23).

[0040] The grid (25) has an upper surface (25a) located upstream of the X-ray (Lx), a lower surface (25b) located downstream of the X-ray (Lx), and a plurality of holes (25h) extending from the upper surface (25a) to the lower surface (25b). The holes (25h) may have an elongated shape. For example, the length of the holes (25h) may be more than twice the width of the hole entrance or hole exit. As illustrated in FIGS. 3a and 3b, the holes (25h) may be arranged at regular intervals. The holes (25h) may be arranged, for example, in a two-dimensional Bravis lattice structure. There are five types of two-dimensional Bravis lattice structures depending on the arrangement of lattice points: a parallelogram system (or oblique system), a rectangular system, a rhombic system, a hexagonal system, and a square system. By arranging the holes (25h) in a Bravis lattice structure, X-rays can be irradiated uniformly in the irradiation area. However, the present invention is not necessarily limited thereto, and the holes (25h) may be arranged irregularly with irregular spacing.

[0041] In the drawings, the holes (25h) are depicted as having a circular shape, but the present disclosure is not limited thereto, and the cross-section of the holes (25h) may be elliptical or polygonal.

[0042] The grid (25) may be formed from a material that blocks X-rays (Lx), and, although not specifically limited, may be formed from, for example, a tungsten alloy. The thickness of the grid (25) may be changed depending on the material forming the grid (25), and accordingly, the length of the holes (25h) may also be changed. For example, if the grid (25) is formed from a material that blocks X-rays better, the thickness of the grid (25) may be reduced, and accordingly, the length of the holes (25h) may also be reduced. Conversely, if the grid (25) is formed from a material that does not block X-rays well, the thickness of the grid (25) may be increased to block X-rays, and accordingly, the length of the holes (25h) may also be increased.

[0043] Meanwhile, the grid (25) may be formed as a single unit, but is not limited thereto. For example, the grid (25) may be manufactured by assembling multiple modules. Accordingly, the grid (25) may be divided into multiple modules and separated, and may be replaced on a module-by-module basis.

[0044] As illustrated in FIG. 2, the holes (23h) are arranged radially from the upper surface (25a) toward the lower surface (25b). That is, the holes (23h) can be arranged parallel to the direction of travel of the X-ray (Lx) from the center of the target (21) toward the grid (25), thereby reducing X-ray loss due to interference between the X-ray (Lx) passing through the holes (25h) of the grid (25) and the grid (25). The holes (25h) can be arranged in a continuous direction from the center of the target (21) where the X-ray (Lx) is generated toward the center of the entrance of each hole (25h).

[0045] The holes (23h) may have an elongated shape, and the sizes of the inlet and outlet may be the same or different. In certain embodiments, the inlet may be smaller than the outlet. The sizes of the inlet and outlet will be described in detail later with reference to FIGS. 4a and 4b.

[0046] The lower surface (25b) may include a convex surface (25d) having a first radius of curvature (R1). The exits of the holes (25h) may be placed on the convex surface (25d). The lower surface (25b) may have a spherical shape having the first radius of curvature (R1) overall, but the present invention is not limited thereto. For example, the spherical surface having the first radius of curvature (R1) may be limited to a portion of the area where the holes (25h) are placed, and the area other than said portion is not particularly limited to the radius of curvature.

[0047] Meanwhile, as illustrated in FIGS. 2 and 3a, the upper surface (25a) may include a concave surface (25u) having a second radius of curvature (R2). The entrances of the holes (25h) may be placed on the concave surface (25u). As illustrated in FIGS. 2 and 3a, the concave surface (25u) may be surrounded by a surface or a flat surface having a radius of curvature different from the second radius of curvature (R2). The concave surface (25u) may be formed in a portion of the area where the holes (25h) are formed, but the present invention is not necessarily limited thereto.

[0048] By forming a concave surface (25u) on the upper surface (25a), the holes (25h) can be formed to have generally equal lengths. In one embodiment, the first radius of curvature (R1) and the second radius of curvature (R2) may be the distance from the center of the target (21) where X-rays (Lx) are generated to the convex surface (25d) and the concave surface (25u), respectively. Since the concave surface (25u) is positioned closer to the target (21) than the convex surface (25d), the second radius of curvature (R2) may be formed to be smaller than the first radius of curvature (R1). For example, the second radius of curvature (R2) may be smaller than the first radius of curvature (R1) by the thickness of the grid (25) or the length of the hole (25h). The centers of the first radius of curvature (R1) and the second radius of curvature (R2) may coincide with the center of the target (21), and accordingly, the holes (25h) arranged radially from the center may all have the same length.

[0049] The grid (25) may be fixed, but the present disclosure is not limited thereto, and may be capable of rotating or moving linearly mechanically or electromagnetically. The spatial division X-ray may be dynamically changed according to the change in position of the grid (25).

[0050] FIG. 4a is a schematic cross-sectional view illustrating a hole (25h) of a grid (25) according to one embodiment of the present invention.

[0051] Referring to FIG. 4a, in this embodiment, the hole (25h) is aligned in the direction of X-ray propagation, and the hole (25h) has an exit on the lower surface having a first radius of curvature (R1) and an entrance on the upper surface having a second radius of curvature (R2). The length (t) of the hole (25h) is equal to the thickness of the grid of the area where the hole is placed. The center (Ct) of the first radius of curvature (R1) and the second radius of curvature (R2) may be the center of the target. Thus, the second radius of curvature (R2) may be smaller than the first radius of curvature (R1) by the thickness of the grid, i.e., the length (t) of the hole.

[0052] In this embodiment, the size of the entrance and exit of the X-ray are generally the same. That is, the length (W1) of the exit of the hole (25h) on the lower surface of the spherical shape having a first radius of curvature (R1) may be generally the same as the length (W2) of the entrance of the hole (25h) on the upper surface of the spherical shape having a second radius of curvature (R2). Here, W1 and W2 represent the lengths on the spherical surface, respectively, but since the size of the hole (25h) is extremely small compared to the first and second radii of curvature (R1, R2), they can be approximated as the widths of the entrance and exit of the hole (25h). Hereinafter, W1 and W2 will be described as the widths of the entrance and exit, respectively, except in special cases.

[0053] In this embodiment, since the holes (25h) are arranged in a radial direction, X-rays emitted from the target that enter the entrance of the holes (25h) of the grid are generally emitted to the outside through the exit of the holes (25h).

[0054] FIG. 4b is a schematic cross-sectional view illustrating a hole (25h') of a grid according to another embodiment of the present invention.

[0055] Referring to FIG. 4b, the hole (25h') according to the present embodiment is generally similar to the hole (25h) described with reference to FIG. 4a, but differs in that the width of the exit (W1) is larger than the width of the entrance (W1). For example, the side wall surface of the hole (25h') can be aligned radially from the center of the target (Ct). Accordingly, the entrance width (W2) of the hole (25h') is smaller than the exit width (W1) of the hole (25h').

[0056] In a specific embodiment, the sidewall surface of the hole (25h') can be perfectly aligned radially from the target center (Ct), in which case the difference between the circumferential length (W2) of the entrance of the hole (25h') and the circumferential length (W1) of the exit can be calculated as the product (t·ra) of the radiation angle (ra) of the entrance and the length (t) of the hole (25h'). The closer the difference between the size of the entrance and the size of the exit of the hole (25h') is to the above value (t·ra), the more smoothly the X-rays entering through the entrance can be emitted to the outside through the exit without colliding with the sidewall of the hole (25h'). Since the circumferential lengths of the entrance and exit can be approximated by the entrance width (W2) and the exit width (W1), the difference between the entrance width (W2) and the exit width (W1) can also be approximated by the product (t·ra) of the radiation angle (ra) of the entrance and the length (t) of the hole (25h'). Therefore, by maintaining the difference between the entrance width (W2) and the exit width (W2) within ±10% of the product (t·ra) of the radiation angle (ra) of the entrance and the length (t) of the hole (25h'), it is possible to reduce the impact of X-rays entering the entrance within this range on the sidewall of the hole (25h') or their emission to the outside through the thickness of a portion of the grid other than the hole (25h').

[0057] In the embodiment of FIG. 4a, the sidewalls of the hole (25h) are not aligned in the radial direction, so some of the X-rays entering through the entrance may collide with the sidewalls of the hole (25h), enter the grid through the sidewalls of the hole (25h), and be emitted to the outside through an area other than the exit of the hole (25h). In contrast, in the present embodiment, the sidewalls of the hole (25h') are aligned in the radial direction, so the X-rays entering through the entrance can generally be emitted to the outside through the exit of the hole (25h'). Additionally, X-rays incident on the grid area other than the hole (25h') are generally blocked by a grid of the same thickness, thereby reducing the generation of noise other than spatially divided X-rays.

[0058] FIG. 5 is a simulation diagram showing a general two-dimensional distribution of X-ray radiation dose passing through a collimator (23) and a grid (25), FIG. 6a is a simulation graph showing radiation dose in a one-dimensional line (CL) according to the prior art, and FIG. 6b is a simulation graph showing radiation dose in a one-dimensional line (CL) according to an embodiment of the present invention. The holes (25h) of the grid (25) have a cylindrical shape, and the simulation was performed with the diameter of the inlet and the diameter of the outlet being the same. In addition, the grid according to the prior art has holes arranged parallel to each other on a flat plate, and the grid according to an embodiment of the present invention has holes arranged in a radial direction from the center of the target.

[0059] Referring to FIG. 5, X-rays are spatially divided and irradiated by a collimator (23) and a grid (25). The points (25OL) where X-rays are irradiated through the holes (25h) of the grid (25) are the brightest, and the surrounding rectangular area is the area (23OL) irradiated by X-rays that have passed through the area defined by the collimator (23). The reason radiation dose is detected in the area (23OL) is due to the superposition of light passing through the holes (25h) and X-rays passing through the grid area other than the holes (25h). The radiation dose in the area (23OL) can be reduced by adjusting the material and thickness of the grid. Although the shape of the X-ray radiation dose distribution as shown in FIG. 5 appears similar in the prior art and the present invention, there is a significant difference in the radiation dose irradiated through each hole (25h), which will be explained with reference to FIG. 6a and FIG. 6b.

[0060] Referring to FIG. 6a, it can be seen that when a grid according to the prior art is used, the radiation dose of X-rays passing through the holes (25h) in the peripheral area is at least 20% smaller than the radiation dose of X-rays passing through the holes (25h) in the central area. In contrast, as shown in FIG. 6b, when a grid according to an embodiment of the present invention is used, it can be seen that the difference between the radiation doses of X-rays irradiated through the holes (25h) in the peripheral area and the holes (25h) in the central area is generally uniform, being less than 10% of the maximum radiation dose.

[0061] Meanwhile, the embodiment of FIG. 6b is a simulation performed under conditions where the hole (25h) has a cylindrical shape, that is, conditions where the entrance width (W2) and the exit width (W1) are the same. By limiting the difference between the exit width (W2) and the entrance width (W1) to, for example, within ±10% of ra·t, the radiation dose of X-rays in the region between the points (25OL) corresponding to the holes (25h) can be further reduced.

[0062] Although various embodiments of the present invention have been described above, the present invention is not limited to the various embodiments and features described above, and various modifications and changes are possible within the scope of the technical concept according to the claims of the present invention.

Claims

1. As a grid for forming spatially divided X-rays, An upper surface located on the upstream side of the X-ray; A lower surface located on the downstream side of the X-ray; and It includes a plurality of long holes extending from the upper surface to the lower surface, The above holes are a grid arranged radially from the upper surface toward the lower surface.

2. In Claim 1, The above surface includes a convex surface having a first radius of curvature, and The exits of the above holes are grids placed on the above convex surface.

3. In Claim 2, The above upper surface includes a concave surface having a second radius of curvature, and The entrances of the above holes are grids placed on the above concave surface.

4. In Claim 3, The second radius of curvature is a grid smaller than the first radius of curvature.

5. In Claim 4, The first radius of curvature and the second radius of curvature are each a grid representing the distance from the center of the target where X-rays are generated to the convex surface and the concave surface.

6. In Claim 1, The above holes are a grid having the same length as each other.

7. In Claim 1, The above holes are a grid arranged in a continuous direction from the center of the target where X-rays are generated to the center of the entrance of each hole.

8. In Claim 7, A grid in which the entrance width of the above holes is equal to or smaller than the exit width of the above holes.

9. In Claim 8, A grid in which the inlet width of the holes is smaller than the outlet width of the holes, and the difference between the inlet width and the outlet width is within ±10% of the product (t·ra) of the inlet angle (ra) of the holes and the length (t) of the holes.

10. In Claim 1, A grid in which the difference in X-ray radiation doses irradiated through the above holes is less than 10% of the maximum radiation dose.

11. In Claim 1, The cross-section of the above holes is a grid that is circular, elliptical, or polygonal.

12. In Claim 1, The above grid includes a plurality of detachable modules and is a grid that is replaceable on a module-by-module basis.

13. In Claim 1, The above grid is capable of rotating or moving linearly mechanically or electromagnetically, and A grid capable of dynamically changing spatially partitioned X-rays according to changes in position.

14. X-ray target that generates X-rays by an electron beam; A collimator that limits the irradiation area of ​​X-rays generated from the above X-ray target; It includes a grid positioned downstream of the above-mentioned collimator, The above grid is a radiation therapy device that is a grid described in any one of claims 1 to 10.

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