A collimating device and method for mini-beam radiotherapy with adjustable slit width

Abstract

The application discloses a collimating device and method for flexible adjustment of slit width of mini-beam radiotherapy, which comprises a fixed base, a single-axis translation table driving system, a first collimating plate and a second collimating plate, wherein the fixed base is installed at the outlet of a heavy ion, proton or photon beam; the single-axis translation table driving system with micro-step precision is carried on the fixed base, wherein the single-axis translation table driving system comprises a guide rail system, a driving motor and an external controller; the first collimating plate is fixedly installed on the fixed base; the second collimating plate is parallelly attached to the first collimating plate, the second collimating plate is arranged on the guide rail system, one end of the second collimating plate is connected to the driving motor, and the driving motor is connected to the external controller; and the first collimating plate and the second collimating plate are provided with an initial slit array with the same longitudinal equal intervals. Therefore, the application can realize continuous dynamic adjustment of slit width of various particle mini-beams.

Description

Technical Field

[0001] This invention relates to the field of radiation field space segmentation technology in radiotherapy, specifically to a collimation device and method for mini-beam radiotherapy with flexibly adjustable slit width. Background Technology

[0002] Currently, radiotherapy, represented by photons, protons, and heavy ions, has become one of the core methods for precision cancer treatment. In recent years, spatially fractionated radiation therapy (SFRT) and its representative minibeam radiation therapy (MBRT) have received widespread attention. This radiotherapy technique uses physical collimation to divide a wide-field beam into a series of submillimeter-level minibeams with high dose gradients and spatially alternating peak-valley distributions. This significantly improves dose tolerance in normal tissues without reducing the control rate of the tumor target area.

[0003] Currently, the main method for achieving mini-beams is to use static physical slit collimators made of high atomic number materials such as copper and tungsten alloys. However, existing mini-beam collimation technologies still have the following prominent problems in clinical trials and applications: 1) Poor adjustment flexibility and low experimental efficiency: Most existing collimators are designed with fixed dimensions, and their slit width and center distance are locked after processing. In experiments exploring optimal biological effects (such as the bystander effect), if the slit width needs to be changed, it is necessary to re-process heavy metal blocks of different specifications and manually replace them in the treatment room. This not only significantly increases experimental costs and time, but the frequent disassembly and assembly process is also prone to introducing geometric alignment deviations, resulting in poor repeatability of dose distribution. 2) Difficulty in guaranteeing the processing accuracy of ultra-high aspect ratio micro slits: Whether it is a high-energy photon, proton, or heavy ion beam, in order to achieve effective radiation shielding, the collimator usually needs a large physical thickness (such as more than 60 mm). When fabricating extremely narrow slits (≤0.3mm) on such thick metal materials using traditional processes (such as wire EDM), it is extremely difficult to guarantee the perpendicularity, parallelism, and consistency of the slit width of the slit walls. Dose distribution distortions caused by fabrication errors are often impossible to correct with software in subsequent experiments, severely limiting the possibility of exploring mini-beam radiotherapy at a finer scale. 3) Lack of means to independently control dose distribution parameters: In existing mini-beam experiments, slit width and center-to-center distance often conflict. If irradiation conditions need to be changed, researchers find it difficult to independently change one parameter on the same physical device without affecting the other. It is worth noting that while adjustable collimators for non-destructive testing or conventional radiotherapy exist (such as four-panel variable apertures or dual-gate slit adjusters), these solutions can only achieve independent adjustment of a single slit width and cannot generate a periodic mini-beam array, or maintain an absolutely constant beam array center distance during adjustment. Therefore, they are not suitable for preclinical mini-beam studies that require precise and repeatable control of peak-valley dose spatial distribution. The lack of the aforementioned parameter adjustment methods prevents researchers from using the "high-dose peak deposition volume" (i.e., slit width) as a single variable for smooth dynamic scanning, which severely restricts the accurate quantitative research on spatial fractionation radiotherapy before clinical trials.

[0004] Therefore, developing a multi-particle compatible mini-beam collimation device that can achieve micron-level effective suture width adjustment using relatively wide physical processing dimensions, has dynamic compensation capability for manufacturing errors, and can maintain an absolutely constant beam center distance is of great scientific research value and clinical application significance for improving the accuracy and experimental efficiency of mini-beam radiotherapy. Summary of the Invention

[0005] This invention aims to solve at least one of the technical problems existing in the prior art. Therefore, in response to the above-mentioned problems, the purpose of this invention is to provide a collimation device and method for minibeam radiotherapy with flexible adjustable slit width. This method achieves continuous dynamic adjustment of the slit width of minibeams, including those for photons, protons, or heavy ions, by precisely stacking and unidirectionally sliding two identically arranged grating plates, while maintaining an absolutely constant center distance between adjacent minibeams. Simultaneously, it utilizes dynamic mechanical misalignment to compensate for static processing errors, solving the technological challenge of processing sub-millimeter-level extremely narrow slits on thick heavy metal surfaces, thereby enabling precise and efficient spatial fractionation radiotherapy (SFRT) technology research and clinical application.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: In a first aspect, the present invention provides a collimation device for mini-beam radiotherapy with a flexibly adjustable slit width. The collimation device includes a fixed base, a single-axis translation stage drive system, a first collimation plate, and a second collimation plate, wherein: The fixed base is installed at the exit of the heavy ion, proton or photon beam; the fixed base is equipped with the single-axis translation stage drive system with micron-level stepping accuracy, wherein the single-axis translation stage drive system includes a guide rail system, a drive motor and an external controller; The first collimation plate is fixedly installed on the fixed base; The second collimator is attached parallel to the first collimator and is disposed on the guide rail system. One end of the second collimator is connected to the drive motor, and the drive motor is connected to the external controller. The first collimator and the second collimator have the same initial slit array with equal longitudinal spacing.

[0007] In some possible implementations, the fixing base adopts a frame structure, and the first alignment plate is fixedly mounted on the frame structure by bolt fastening or embedded clamping, so that the outer surface of the first alignment plate is flush with the front surface of the frame structure.

[0008] In some possible implementations, the outer surface of the frame structure is marked with a reference crosshair that matches the laser positioning system of the radiotherapy room for geometric positioning; the fixed base is mounted on a base, and the base integrates a manual multi-dimensional fine-tuning stage, which allows adjustment of the fixed base's translation in the X and Y directions and its angular deflection around the Z axis.

[0009] In some possible implementations, the guide rail system is located on top of the fixed base. The guide rail system is a heavy-duty precision crossed roller guide or a heavy-duty linear guide, used to suspend and support the second alignment plate, limiting its displacement sag and structural deformation during lateral translation under rated load.

[0010] In some possible implementations, the single-axis translation stage drive system further includes a backlash-free transmission assembly with pre-tightening and backlash elimination function, and the second collimator is connected to the drive motor through the backlash-free transmission assembly.

[0011] In some possible implementations, a high-resolution optical displacement sensor is mounted between the first collimator and the second collimator. The high-resolution optical displacement sensor is connected to the external controller. The high-resolution optical displacement sensor acquires the absolute physical coordinates of the second collimator relative to a fixed reference in real time and transmits them as a feedback signal to the external controller to form a full closed-loop position control.

[0012] In some possible implementations, the high-resolution optical displacement sensor employs an absolute optical grating ruler or a magnetic grating ruler.

[0013] In some possible implementations, both the first and second collimators are made of high atomic number and high density materials such as pure copper, tungsten alloy, or lead. The flatness and surface roughness of the mating surfaces of the first and second collimators must meet the requirements of smooth contact and seamless mating.

[0014] Secondly, the present invention also provides a method for dynamically adjusting the slit width of a collimation device for flexible and adjustable slit width in mini-beam radiotherapy, characterized in that the method includes: Obtain the processing deviation value; Input mini-beam array target effective width ; The external controller obtains the measured physical seam width based on the processing deviation value. Based on the measured physical seam width and target effective width Calculate the compensation driving displacement Δx= - And send commands to the single-axis translation stage drive system according to the compensation drive displacement; The single-axis translation stage drive system drives the second collimator to make it laterally translate relative to the first collimator in a direction perpendicular to the slit, thereby compensating for the displacement. Through the physical misalignment and blocking of the slit between the two plates, a mini-beam array with the target effective width is obtained. The above process is repeated to achieve dynamic adjustment of the slit width.

[0015] In some possible implementations, the step of obtaining the processing deviation value is as follows: Manufacture the first and second alignment plates and determine the initial machining reference seam width.

[0016] The actual physical widths of the first collimator and each initial slit of the first collimator are measured to obtain the measured physical widths. ; The measured width With design reference width By comparison, the processing deviation value σ is calculated. - .

[0017] Because the present invention adopts the above technical solution, it has the following characteristics: 1. Improve experimental efficiency and operational flexibility: This invention solves the physical limitation of the need to frequently change large-mass metal collimators in the research and clinical application of traditional mini-beam radiotherapy technology, realizes in-situ dynamic switching of different suture width parameters, shortens the experimental preparation cycle and simplifies the operation process.

[0018] 2. Achieving physical decoupling of spatial dose parameters: This invention fixes the center-to-center distance between adjacent beams through a double-layer plate geometry, allowing researchers to independently adjust the slit width (i.e., peak deposition volume) as a single variable. This provides a reliable hardware foundation for quantitatively studying radiobiological mechanisms such as the bystander effect of photons, protons, and heavy ions.

[0019] 3. Reduce processing difficulty and compensate for manufacturing errors: This invention uses the mechanical displacement of a stepper motor to perform dynamic closed-loop compensation for the static processing deviation of the straight plate, which solves the process problem of directly processing sub-millimeter-level narrow slits on thick (e.g., 60mm) high-density materials, and reduces the dependence of the device on processing accuracy and manufacturing cost.

[0020] 4. Ensuring the spatial characteristics of dose distribution: The present invention adopts a precision-ground flat and fitted interface design, which maintains the continuity of physical shielding during the dynamic adjustment of slit width, limits the scattering of primary rays and the lateral leakage of secondary particles, and ensures that the output mini-beam array has a steep edge dose gradient and a low valley dose background.

[0021] 5. Versatility and expandability with multiple particle types: The device of this invention has a compact mechanical structure and stable operation. By adapting the material and physical thickness of the collimator, it is not only suitable for heavy ion radiotherapy, but can also be comprehensively expanded to the technical research and clinical application of photon, proton mini-beam radiotherapy and combined with ultra-high dose rate (FLASH) radiotherapy.

[0022] In summary, the collimation device and method of the present invention, which has adjustable width and constant center distance for mini-beam radiotherapy, can be widely applied to mini-beam spatial fractionation radiotherapy, including photon, proton, or heavy ion therapy. Attached Figure Description

[0023] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. In the drawings: Figure 1 This is a simplified diagram of the overall structure of the collimation device according to an embodiment of the present invention; Figure 2 This is a schematic diagram illustrating the geometric misalignment and error compensation principle of the double-layer collimator in an embodiment of the present invention. Figure 3 This is a schematic diagram of the one-dimensional mini-beam distribution curves before and after dynamic adjustment of the collimator according to an embodiment of the present invention; Figure 4 This is a flowchart of the slit width dynamic adjustment method according to an embodiment of the present invention. Detailed Implementation

[0024] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a specific order as described or illustrated, unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0025] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0026] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "above," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure.

[0027] How to develop a multi-particle compatible mini-beam collimation device and method that can achieve micron-level effective slit width adjustment using relatively wide physical processing dimensions, possess dynamic compensation capability for manufacturing errors, and maintain an absolutely constant beam center distance? This invention provides a collimation device and method for mini-beam radiotherapy with flexibly adjustable slit width, comprising: a fixed base, a single-axis translation stage drive system, a first collimating plate, and a second collimating plate. The fixed base is installed at the exit of a heavy ion, proton, or photon beam. The fixed base is equipped with a single-axis translation stage drive system with micron-level stepping accuracy, which includes a guide rail system, a drive motor, and an external controller. The first collimating plate is fixedly installed on the fixed base. The second collimating plate is parallel to and attached to the first collimating plate, and is disposed on the guide rail system. One end of the second collimating plate is connected to the drive motor, which is connected to the external controller. The first and second collimating plates have the same longitudinally equidistant initial slit array. Therefore, this invention can achieve continuous dynamic adjustment of the slit width of mini-beams for various particle beams.

[0028] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0029] In this invention, a Cartesian coordinate system is used as a reference: X-axis: a horizontal axis perpendicular to the long axis of the slit, i.e., the direction of the slit width and the relative sliding direction of the second collimator; Y-axis: a vertical axis along the long axis of the slit, i.e., the longitudinal extension direction of the slit array; Z-axis: along the central axis of the accelerator beam, i.e., the beam travel direction. The X-axis and Z-axis form a horizontal plane, and the Y-axis is a vertical direction. The surfaces of both the first and second collimators are located in the XY plane, and the beam passes through the collimators along the positive Z-axis. Laser isocentric positioning reference lines are distributed on the outer X- and Y-direction surfaces of the fixed base, aligned with the X- and Y-direction laser positioning lines of the treatment chamber, respectively.

[0030] Example 1: As Figure 1As shown, the collimation device for flexibly adjustable slit width in mini-beam radiotherapy provided in this embodiment includes a fixed base 1, a single-axis translation stage drive system 2, a first collimation plate 3, and a second collimation plate 4, wherein: Fixed base 1 is installed at the exit of the heavy ion, proton or photon beam; The fixed base 1 is equipped with a single-axis translation stage drive system 2 with micron-level stepping accuracy for displacement in the X-axis direction. The single-axis translation stage drive system 2 includes a guide rail system 21, a drive motor 22, a backlash-free transmission component 23, and an external controller 24. The motion mode is controlled in a closed loop by the external controller 24 to ensure the accuracy of the displacement.

[0031] The first collimating plate 3 is fixedly installed on the fixed base 1, wherein the surface of the first collimating plate 3 is provided with an initial slit array 31 arranged longitudinally at equal intervals.

[0032] The second collimator 4 is parallel and tightly fitted to the front or rear end of the first collimator 1 and is mounted on the guide rail system 21. One end of the second collimator 4 is connected to the drive motor 22 via a backlash-free transmission assembly 23, and the drive motor 22 is connected to an external controller 24. The geometric dimensions, material, initial width of the slits, and center-to-center distance of the second collimator 4 are absolutely consistent with those of the first collimator 4.

[0033] In a preferred embodiment of the present invention, the fixed base 1 can adopt a frame structure. The central opening area of ​​the frame structure corresponds to the slit array distribution area of ​​the collimating plate, allowing the collimated mini-beam to be projected downstream without obstruction. The frame structure is integrally formed from a high-strength alloy (such as hard aluminum alloy or stainless steel) or reinforced with a reinforcing rib structure to ensure overall mechanical rigidity. The inner surface of the frame structure is machined with a precision positioning groove. The first collimating plate 3 is fixed in the positioning groove by bolt fastening or embedded clamping, so that the outer surface of the first collimating plate 3 is flush with the front surface of the frame.

[0034] Furthermore, the outer surface of the frame structure is marked with reference crosshairs that match the laser positioning system in the radiotherapy room, for the overall geometric alignment of the device.

[0035] Furthermore, the fixed base 1 can also be bolted to the base, which integrates a manual multi-dimensional fine-tuning stage (including X-axis translation, Y-axis translation, and rotation around the Z-axis) for precise geometric alignment of the device with the beam isocenter before the experiment. The manual multi-dimensional fine-tuning stage includes multiple precision micrometer-driven multi-degree-of-freedom manual adjustment platforms, allowing the operator to manually adjust the fixed base's translation in the X and Y directions and its angular deflection around the Z-axis by manually rotating the micrometer without motor drive, until all reference lines on the fixed base 1 are completely aligned with the laser line in the treatment room.

[0036] In a preferred embodiment of the present invention, the guide rail system 21 is disposed on the top of the fixed base 1. The guide rail system 21 may be a heavy-duty precision cross roller guide or a heavy-duty linear guide, used to suspend and support the second collimator 4, and limit its displacement sag and structural deformation when it is laterally translated under rated load.

[0037] In a preferred embodiment of the present invention, in order to meet the micron-level precision displacement adjustment requirements within the sub-millimeter stroke, the drive motor 22 can use a backlash-free transmission component 23 with pre-tightening backlash-free function (such as a double-nut pre-tightening backlash-free ball screw module) to realize backlash-free precision transmission of the second collimator 4. This rigid connection structure eliminates the mechanical backlash generated during drive reversal from a physical design perspective, which is the basis for ensuring the spatial consistency of the Minibeam slit width and the repeatability of operation.

[0038] In a preferred embodiment of the present invention, a high-resolution optical displacement sensor 5 is assembled between the first collimator 3 and the second collimator 4. The high-resolution optical displacement sensor 5 is connected to an external controller 24 to realize closed-loop feedback control of absolute position. Specifically, the high-resolution optical displacement sensor 5 acquires the absolute physical coordinates of the second collimator 4 relative to a fixed reference in real time and transmits them as feedback signals to the external controller 34, thus forming a closed-loop position control. This mechanism not only ensures the accuracy of displacement command execution but also provides real-time position locking and dynamic correction when materials experience thermal effects due to photon, proton, or heavy ion beam irradiation or encounter environmental micro-vibrations.

[0039] Furthermore, the high-resolution optical displacement sensor 5 can be an absolute optical grating ruler or a magnetic grating ruler.

[0040] In a preferred embodiment of the present invention, the first collimator 3 and the second collimator 4 are shielding and collimation components for realizing spatial modulation of beams such as photons, protons or heavy ions, and can be heavy metal collimators with high thickness (e.g., 60 mm) and large mass (more than 5 kg per single layer).

[0041] Furthermore, to effectively block primary rays in the untransmitted region and reduce background dose, both the first collimator 3 and the second collimator 4 can be made of high atomic number (High-Z) and high-density materials such as pure copper, tungsten alloy, or lead. The thickness of the single-layer or stacked physical blocking layer along the beam direction (Z-axis) is set according to the beam type and energy (usually in the range of 30-60 mm). For proton or heavy ion beams (such as 400 MeV / u carbon ions), this thickness must be greater than the maximum physical range of the particle's Bragg peak in the corresponding material; for high-energy photon beams, this thickness must meet the attenuation rate standards for X-rays of that energy required for clinical applications.

[0042] Furthermore, this embodiment can employ a high aspect ratio machining strategy: when directly machining sub-millimeter (e.g., 0.3 mm) minibeam transmission slits on a fixed base with a thickness of up to 60 mm, the aspect ratio can reach 200:1. When machining using processes such as wire electrical discharge machining (WEDM), the inner wall of the slit is prone to machining defects such as "bulging" or "tapering" due to the influence of electrode wire tension deformation, chip removal, and thermal deformation, affecting the parallelism of the beam transmission. Therefore, this invention sets the initial slit width of the two collimating plates to a relatively large size (e.g., 0.5-1.0 mm) to ensure perpendicularity and surface roughness, and sets the center distance between adjacent slits to a required fixed value (e.g., 3.6 mm). The target slit width is achieved through the relative mechanical misalignment of the double-layer collimating plates, reducing the precision requirements of static physical machining. All machining dimensions are based on this example, but are not limited to it; dimensions can be selected according to actual needs.

[0043] Furthermore, the second collimator 4 needs to slide horizontally on the surface of the first collimator 3 with a stroke of sub-millimeter level. To limit the lateral leakage and scattering of primary rays or secondary radiation along the mechanical gap between the two plates, the rear surface of the first collimator 3 and the front surface of the second collimator 4 need to be precision ground. The flatness and surface roughness (e.g., Ra ≤ 0.8μm) of their relative contact surfaces must meet the requirements of smooth contact and seamless fit. This surface contact design avoids the geometric escape path of stray radiation, while reducing the static friction of the sliding surface, ensuring the micron-precision displacement command of the synchronous drive motor in response to mechanical changes.

[0044] Example 2: This example also provides a method for dynamically adjusting the slit width. A single-axis translation stage drive system 2 can drive a second collimating plate 4, causing it to undergo a slight lateral translation relative to the first collimating plate 3 along a direction perpendicular to the slit (X-axis). Through the physical misalignment and blocking of the initial slits of the two plates, a dynamic minibeam array with continuously reduced effective transmission width is obtained. The dynamic slit width adjustment method is the physical modulation mechanism of this invention for decoupling the spatial distribution parameters of the minibeam, specifically as follows: Spatial parameter decoupling based on mechanical interference: In a traditional single collimator, the slit width and center distance are coupled static properties. This invention uses an external controller 24 to input a lateral displacement command to control the drive motor 22, causing the second collimator 4 to shift by Δx. Due to the periodic consistency of the slit arrangement in the two plates, each edge of the transmission window of the first collimator 3 is blocked by the same-side edge of the corresponding shielding area of ​​the second collimator 4. Therefore, the physical width of all transmission mini-beams in the entire array is synchronously reduced. During the misalignment blocking process, the geometric center lines of adjacent effective transmission beams are translated by Δx / 2 in the absolute spatial coordinate system, but the relative distance d between the beams (i.e., the array center distance ctc) is physically fixed by the geometric configuration of the double-layer plates, remaining unchanged at the initial set value (e.g., 3.6 mm). This mechanism achieves independent control and decoupling of two key physical parameters: "deposited dose volume (slit width)" and "source spacing (center distance)".

[0045] Control of beam penumbra: When using thick metal plates to truncate high-energy photon, proton, or heavy ion beams, edge scattering easily leads to beam penumbra broadening. This invention relies on a flat, dynamically bonded interface. When the second collimator 4 cuts into the original beam space, the first collimator 3 and the second collimator 4 remain seamlessly connected in terms of physical blocking thickness. This allows the dynamically adjusted sub-millimeter mini-beam (e.g., 0.2mm or 0.3mm) to still possess a relatively steep dose gradient, effectively suppressing edge scattering and secondary particle contamination, and ensuring the spatial distribution quality of the dose in the mini-beam peak region.

[0046] Continuous dynamic adjustment of peak-valley dose ratio (PVDR): Based on micron-level precision control within sub-millimeter ranges, smooth physical parameter scanning can be performed via control commands without entering the radiation shielding room to replace hardware. This method can continuously adjust the core dosimetric parameter of spatial fractionation radiotherapy—the peak-valley dose ratio (PVDR = Peak dose / Valley dose, PVDR = ...). PVDR is a core dosimetric indicator in spatially fractionated radiotherapy. Under the condition that the center-to-center distance (CTC) between adjacent beams remains constant, the effective slit width directly determines the size of the peak dose deposition volume: when the slit width decreases, the peak cross-sectional area of ​​each mini-beam shrinks, and the peak dose becomes more concentrated. However, the valley regions between adjacent peak regions receive less scattered and transmitted dose due to the additional obstruction of the collimator, leading to a further decrease in valley dose and thus an increase in PVDR. Conversely, when the slit width increases, the peak regions widen, the valley dose increases, and the PVDR decreases. Therefore, this invention, by continuously adjusting the slit width, can achieve continuous and predictable control of PVDR under the same center-to-center distance. Thus, this invention not only enables continuous adjustment of PVDR but also efficiently acquires biological survival data under different slit widths, expanding the experimental conditions for exploring the spatial diffusion characteristics of the bystander effect of radioactive beams (photons, protons, or heavy ions).

[0047] Specifically, during the manufacturing of the collimator, a physical aperture larger than the target mini-beam width is used as the processing reference. After measuring the actual processing error, the error value is fed back to the single-axis translation stage drive system for displacement calculation. Using misalignment interference, a mini-beam with an extremely narrow target width is precisely output. This method aims to compensate for static manufacturing deviations through mechanical displacement, such as... Figure 4 The specific implementation process and physical mechanism are as follows: I. Offline calibration of machining deviation: 1.1 Manufacture the first alignment plate 3 and the second alignment plate 4, and determine the initial machining reference seam width.

[0048] Specifically, during the processing stages of the first collimator 3 and the second collimator 4, for shielding materials with a large thickness (e.g., 60 mm), a wide slot size (e.g., 0.5-1.0 mm) that is easier to ensure perpendicularity and parallelism is used as the initial processing reference slot width. .

[0049] 1.2 Using a high-precision optical measuring microscope or limit gauge, the actual physical width of the first collimator and its initial slit is measured to obtain the measured physical width of the slit. .

[0050] 1.3 Input the machining deviation value into the error compensation database of the external controller 24.

[0051] Specifically, the calculation of the processing deviation value: the actual physical width of the slit. With design reference width Compare and calculate the processing deviation value σ (σ= - The micron-level deviation value σ (such as the 0.02mm error caused by the actual slit width being 0.52mm and deviating from the design value by 0.50mm) is recorded and entered into the error compensation database of the external controller 24.

[0052] II. Target setting and displacement superposition calculation: 2.1 Input the target effective width of the mini-beam biology experiment .

[0053] Specifically, the target mini-beam width set in the experiment was... (e.g., 0.3 mm).

[0054] 2.2 External controller 24 obtains the actual physical seam width based on the processing deviation value. And based on the actual physical seam width and target effective width Perform displacement superposition to calculate the final compensated driving displacement.

[0055] Specifically, the external controller 24 obtains the actual physical seam width based on the processing deviation value. (0.5mm + 0.02mm), rather than simply using the theoretical seam width value (such as 0.5mm), and based on the actual physical seam width. and target effective width The formula for calculating the driving displacement Δx by performing displacement superposition is: Δx = - By controlling the relative mechanical displacement of the second collimator 4, the excess slit width, including the allowance and processing error, is blocked outside the effective transmission field.

[0056] III. Closed-loop drive and precision misalignment: 3.1 The external controller 24 sends drive commands to the single-axis translation stage drive system.

[0057] Specifically, before the beam irradiation experiment, the calculated driving displacement Δx is executed through a precision drive system.

[0058] 3.2 The drive motor 22 drives the second collimator 4 to move laterally, and changes the width of the transmission zone by the misalignment of the initial slits of the two collimators.

[0059] 3.3 The grating ruler reads the absolute position coordinates of the second collimating plate 4 in real time, and checks whether the displacement is Δx and the error is less than or equal to 1um. If so, proceed to the next step.

[0060] IV. Physical Output and Experimental Verification: 4.1 Lock the mechanical position of the single-axis translation stage drive system 2 and start the heavy accelerator for beam irradiation.

[0061] 4.2 The output center distance is strictly constant and the width is Miniature beam array.

[0062] Specifically, based on the design logic of "wide slit processing and narrow slit transmission", the micron-level processing error (such as 20μm) that is difficult to avoid on a single-layer collimation plate is converted into a micron-level feed compensation amount for the drive motor in the double-layer misalignment structure. This method ensures the physical slit width accuracy and spatial distribution consistency of the final output photon, proton or heavy ion mini beam at the sub-millimeter scale.

[0063] In summary, this invention combines a double-layered, parallel collimator with a high-precision single-axis displacement stage drive system. Based on the principle of mechanical misalignment and shielding, it achieves dynamic and continuous adjustment of the slit width while maintaining a constant center distance of the mini-beam array. The device employs a "wide slit processing, narrow slit transmission" strategy, coupled with a position closed-loop error compensation algorithm, which effectively reduces the processing difficulty of deep narrow slits in thick collimators. This provides a high-precision beam spatial modulation scheme for photon, proton, and heavy ion spatial fractionation radiotherapy that meets the needs of experimental and clinical validation.

[0064] The application of the collimation device and method for flexible adjustable slit width in mini-beam radiotherapy according to the present invention will be described in detail below through specific embodiments.

[0065] S1. Installation and Alignment: In this embodiment, at the beam outlet of the radiotherapy room, the fixed base 1 is installed on the beam axis using a manual multi-dimensional fine-tuning stage on the base. The single-axis translation stage drive system 2, with micron-level stepping accuracy, is mounted on the fixed base 1. The geometric alignment steps are as follows: First, turn on the laser positioning system in the treatment room to generate X and Y direction laser crosshairs; Then, by manually rotating the micrometer heads of each axis of the multi-dimensional micro-adjustment stage, the fixed base 1 is adjusted in X-axis translation, Y-axis translation, and angular deflection around the Z-axis, so that the reference crosshairs on the outer surface of the fixed base 1 are completely aligned with the laser positioning lines of the treatment room.

[0066] After adjustment, lock all degrees of freedom of the fine-tuning stage. At this point, the center of the collimator's slit array is precisely geometrically aligned with the accelerator beam isocenter. The purpose of this geometric alignment is to ensure that the beam center axis passes perpendicularly through the geometric center of the collimator plane, and to ensure that the mini-beam array modulated by the collimator is symmetrically distributed about the beam axis, thereby avoiding dose distribution asymmetry and target coverage deviation caused by geometric misalignment.

[0067] S2, Collimation plate manufacturing: The first collimator 3 (fixed layer) and the second collimator 4 (movable layer) are manufactured using materials such as pure copper or tungsten alloy. The physical thickness is set to meet attenuation and blocking requirements based on the beam type (photons, protons, or heavy ions) and energy. An initial array of slits with consistent geometric arrangement is machined on the two collimators using precision wire cutting. The initial slit width is set to a physical reference size to ensure machining accuracy (e.g., 0.5 mm), and the center distance between adjacent slits is set to a fixed value (e.g., 3.6 mm).

[0068] S3. Interface grinding and assembly: The mating surfaces of the two alignment plates are precision ground. The first alignment plate 3 is fixed on the fixed base 1, and the second alignment plate 4 is installed on the guide rail system 21, with its flat surface mating with the first alignment plate 3, to form a double-layer parallel sliding structure with surface contact.

[0069] S4. Offline error calibration: Before the beam irradiation experiment, the average physical slit width, i.e., the measured slit width, of the first and second collimators actually manufactured was read using optical measurement equipment. (For example, due to errors in wire cutting, the actual processing width is 0.52mm), and this processing deviation value is recorded in the error compensation database of the external controller 24.

[0070] S5. Target setting and displacement calculation: The experimenter inputs the effective slit width of the high-dose zone required for the biological experiment into the external controller 24. (For example, 0.30 mm). The external controller 24 calculates the final drive displacement Δx that needs to be compensated. - =0.52mm - 0.30mm = 0.22mm.

[0071] S6, Closed-loop drive and precision misalignment: The drive motor 22 receives external commands and drives the second collimator 4 to move laterally via the backlash-free transmission assembly 23. Under the real-time closed-loop feedback of the grating ruler, the position is locked when the displacement reaches 0.22mm. At this time, the effective width of the transmitted beam is corrected to the target width of 0.30mm through physical misalignment and blocking, while the center distance of the mini-beam array remains unchanged at 3.6mm.

[0072] S7, Physical Output and Irradiation: Turn on the accelerator or radiation source, and use the aforementioned device to dynamically modulate the minibeam array to perform spatial segmentation irradiation experiments on the cell phantoms or animal models behind it.

[0073] S8, Continuous parameter scan: Continuous parameter scanning refers to the process of sequentially inputting a set of different target slit width values ​​(e.g., decreasing from 0.5 mm to 0.1 mm in 0.05 mm increments) through an external controller 24 without entering a radiation shielding room, changing hardware, or interrupting the experimental procedure. The system automatically repeats steps S5 to S7, completing one beam irradiation and data acquisition at each width value, thereby obtaining a complete response curve of "slit width-dose distribution-biological effect". This function makes the slit width the sole independent variable, enabling high-throughput screening of spatially segmented radiotherapy dosimetry parameters and providing a systematic experimental method for quantitatively studying underlying radiobiological mechanisms such as the bystander effect and dose-volume effect in mini-beam radiotherapy.

[0074] In summary, the dynamic collimation device and method provided by this invention, by adjusting the collimation material and thickness parameters, can be applied to the research and clinical application of mini-beam radiotherapy technology using various types of rays such as photons, protons, and heavy ions, and can also be applied to the research and clinical application of technology combined with ultra-high dose rate (FLASH) radiotherapy.

[0075] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. In the description of this specification, the terms "a preferred embodiment," "furthermore," "specifically," "in this embodiment," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the embodiments in this specification. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A collimation device for mini-beam radiotherapy with flexibly adjustable slit width, characterized in that, The alignment device includes a fixed base, a single-axis translation stage drive system, a first alignment plate, and a second alignment plate, wherein: The fixed base is installed at the exit of the heavy ion, proton or photon beam; the fixed base is equipped with the single-axis translation stage drive system with micron-level stepping accuracy, wherein the single-axis translation stage drive system includes a guide rail system, a drive motor and an external controller; The first collimation plate is fixedly installed on the fixed base; The second collimator is attached parallel to the first collimator and is disposed on the guide rail system. One end of the second collimator is connected to the drive motor, and the drive motor is connected to the external controller. The first collimator and the second collimator have the same initial slit array with equal longitudinal spacing.

2. The collimation device for flexibly adjustable slit width in mini-beam radiotherapy according to claim 1, characterized in that, The fixed base adopts a frame structure, and the first alignment plate is fixedly mounted on the frame structure by bolt fastening or embedded clip-on, so that the outer surface of the first alignment plate is flush with the front surface of the frame structure.

3. The collimation device for flexibly adjustable slit width in mini-beam radiotherapy according to claim 2, characterized in that, The outer side of the frame structure is marked with a reference crosshair that matches the laser positioning system of the radiotherapy room for geometric positioning. The fixed base is mounted on the base, which integrates a manual multi-dimensional fine-tuning stage. The manual multi-dimensional fine-tuning stage can be used to adjust the translation of the fixed base in the X and Y directions and the angular deflection around the Z axis.

4. The collimation device for flexibly adjustable slit width in mini-beam radiotherapy according to claim 1, characterized in that, The guide rail system is located on top of the fixed base. The guide rail system adopts heavy-duty precision cross roller guide or heavy-duty linear guide to suspend and support the second alignment plate, limiting its displacement sag and structural deformation when it moves laterally under rated load.

5. The collimation device for flexibly adjustable slit width in mini-beam radiotherapy according to claim 1, characterized in that, The single-axis translation stage drive system also includes a backlash-free transmission component with pre-tightening and backlash elimination function, and the second collimator is connected to the drive motor through the backlash-free transmission component.

6. The collimation device for flexibly adjustable slit width in mini-beam radiotherapy according to claim 1, characterized in that, A high-resolution optical displacement sensor is mounted between the first collimator and the second collimator. The high-resolution optical displacement sensor is connected to the external controller. The high-resolution optical displacement sensor collects the absolute physical coordinates of the second collimator relative to a fixed reference in real time and transmits them to the external controller as a feedback signal to form a full closed-loop position control.

7. The collimation device for flexibly adjustable slit width in mini-beam radiotherapy according to claim 6, characterized in that, The high-resolution optical displacement sensor employs an absolute optical grating ruler or a magnetic grating ruler.

8. The collimation device for flexibly adjustable slit width in mini-beam radiotherapy according to claim 1, characterized in that, Both the first and second collimating plates are made of high atomic number and high density materials such as pure copper, tungsten alloy or lead. The flatness and surface roughness of the mating surfaces of the first and second collimating plates must meet the requirements of smooth contact and seamless mating.

9. A method for dynamically adjusting the slit width of a collimation device for flexible adjustable slit width in mini-beam radiotherapy according to any one of claims 1 to 8, characterized in that, The method includes: Obtain the processing deviation value; Input mini-beam array target effective width ; The external controller obtains the measured physical seam width based on the processing deviation value. Based on the measured physical seam width and target effective width Calculate the compensation driving displacement Δx= - And send commands to the single-axis translation stage drive system according to the compensation drive displacement; The single-axis translation stage drive system drives the second collimator to make it laterally translate relative to the first collimator in a direction perpendicular to the slit, thereby compensating for the displacement. Through the physical misalignment and blocking of the slit between the two plates, a mini-beam array with the target effective width is obtained. The above process is repeated to achieve dynamic adjustment of the slit width.

10. The method for dynamically adjusting the slit width according to claim 9, characterized in that, The steps to obtain the machining deviation value are as follows: Manufacture the first and second alignment plates and determine the initial machining reference seam width. The actual physical widths of the first collimator and each initial slit of the first collimator are measured to obtain the measured physical widths. ; The measured width With design reference width By comparison, the processing deviation value σ is calculated. - .

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