Multi-blade pre-absorber based on particle flash beam adjustment

Abstract

The utility model provides a multi-blade pre-absorber based on particle flash beam adjustment, and relates to the field of medical instruments. Comprising an outer frame, a blade guide groove and a body, the body is composed of blades, blade clamping plates and blade telescopic assemblies, the blades are fixed to one sides of the blade clamping plates, and the blade telescopic assemblies are installed on the other sides of the blade clamping plates. The blade telescopic assembly is fixedly installed on the inner wall of one side of the outer frame, and the blade guide grooves are fixedly installed on the two opposite inner walls of the outer frame in parallel. The number of the bodies is at least two, the blade telescopic assembly can be matched with blades of different thicknesses, and any blade can be flexibly selected according to a subdivision scheme to form combinations of various thicknesses and numbers. The pre-absorber with the fixed thickness is decomposed into a multi-blade combination, the total thickness is not changed, namely, the beam blocking capacity is not changed, the depth control can be more accurate through different blade combination modes of the multi-blade structure, the response speed is improved in cooperation with an energy reducer, and the requirement of the third-generation flash technology is better met.

Description

Technical Field

[0001] The utility model relates to the field of medical technologies, and particularly relates to a multi-leaf pre-absorber based on particle flash beam regulation. Background Art

[0002] Proton therapy has been developed for decades internationally and has numerous applications in China. Pencil beam scanning is the second-generation proton therapy technology after passive scattering. In pencil beam scanning, due to technical limitations, the minimum energy of protons from a general accelerator is 70 MeV to 100 MeV, corresponding to an equivalent water depth of 4 cm to 7.5 cm. The situation of using a pre-absorber is when the therapeutic proton energy is less than the minimum proton energy of the accelerator. For example, for a minimum available energy of 70 MeV, if a pre-absorber is not used to reduce the beam energy, tumors with a position less than 4 cm in equivalent water depth cannot be treated.

[0003] A pre-absorber (also called a range shifter) is generally made of a piece of plastic (such as PMMA, Lexan, Lucite, etc.) or graphite and is placed downstream of the beam exit window of the treatment head. The current pre-absorber is a solid with a fixed thickness and has two positions: retracted and extended. When there is a need for a treatment depth below 4 cm, by blocking the beam energy of 70 MeV, the beam above 70 MeV can reach different depths of 0 - 4 cm.

[0004] Secondary neutrons are generated during the process of the pre-absorber blocking the proton beam. However, due to the low beam intensity of traditional proton therapy (usually within 4 nA), the impact of these secondary neutrons on the healthy tissues of patients is often ignored. The third-generation proton flash (FLASH) therapy technology is a proton therapy technology with an ultra-high dose rate that is different from traditional proton therapy. The beam intensity is dozens or hundreds of times that of traditional proton therapy, and the secondary neutron dose rate generated is also dozens or hundreds of times that of traditional proton therapy. In line with the principle of keeping the irradiation dose of healthy human tissues as low as reasonably feasible, it is necessary to minimize the secondary neutrons generated by the pre-absorber. Therefore, higher requirements are placed on the control accuracy and safety of the beam. The more precise the energy control, the better the healthy tissues outside the tumor can be protected. In view of this situation, a pre-absorber that can be precisely controlled needs to be redesigned. Summary of the Invention

[0005] Aiming at the defects and deficiencies of the prior art, the utility model proposes a multi-leaf pre-absorber based on particle flash beam regulation, which decomposes the pre-absorber with a fixed thickness into a multi-leaf combination. The total thickness remains unchanged, that is, the ability to block the beam remains unchanged. However, different blade combination methods of the multi-leaf structure can make the depth control more precise, cooperate with the energy reducer to improve the response speed, and better meet the requirements of the third-generation flash technology.

[0006] A multi-leaf pre-absorber based on particle flash beam regulation, comprising: an outer frame, a blade guide groove, and a main body; the main body is composed of blades, blade clamping plates, and blade telescopic components, the blades are fixed on one side of the blade clamping plates, and the blade telescopic components are installed on the other side of the blade clamping plates; the blade telescopic components are fixedly installed on one inner wall of the outer frame, and the blade guide grooves are fixedly installed in parallel on two opposite inner walls of the outer frame; the number of the main bodies is at least 2 groups, the blade telescopic components can adapt to blades of different thicknesses, and any blades can be flexibly selected according to the subdivision scheme to form various combinations of thicknesses and quantities.

[0007] The blade telescopic component adopts a parallelogram multi-link structure, driven by a motor and transmitted by a ball screw. It includes a link base, a limit bushing, a link, a bearing, a screw, a coupling, a motor, and a rotating shaft. The link is a parallelogram multi-link composed of a limit bushing and a rotating shaft hinged. One end of the link is fixed on the same side of the link base and the blade clamping plate and can rotate around the limit bushing and the rotating shaft. The bearings on the other two joints can roll in the grooves of the link base and the blade clamping plate respectively under the combined drive of the screw, the coupling, and the motor, controlling the expansion and contraction of the multi-link and enabling the blade to reciprocate in the blade guide groove.

[0008] The beneficial effects of the present utility model:

[0009] The pre-absorber with a fixed thickness is decomposed into a multi-leaf combination, and the total thickness remains unchanged, that is, the ability to block the beam remains unchanged. However, different blade combination methods of the multi-leaf structure can make the depth control more precise, cooperate with the energy reducer to improve the response speed, and better meet the requirements of the third-generation flash technology. Description of the Drawings

[0010] Figure 1 It is the overall structure diagram of the present utility model.

[0011] Figure 2 It is the internal structure diagram of the present utility model.

[0012] Figure 3 It is the structure diagram of a single blade telescopic component of the present utility model.

[0013] In the figure: 1 - outer frame; 2 - blade telescopic component; 5 - blade guide groove; 6 - link base; 7 - blade clamping plate; 8 - limit bushing; 9 - link; 10 - bearing; 11 - screw; 12 - coupling; 13 - motor; 14 - rotating shaft; 15 - blade. Specific Embodiments

[0014] The following further elaborates on the specific embodiments of the present utility model in conjunction with the drawings.

[0015] A multi-leaf pre-absorber based on particle flash beam regulation, as Figures 1-3As shown, the invention comprises: an outer frame (1), a blade guide groove (5), and a body; the body is composed of a blade (15), a blade clamp (7), and a blade telescopic assembly (2); the blade (15) is fixed to one side of the blade clamp (7), and the blade telescopic assembly (2) is installed on the other side of the blade clamp (7); the blade telescopic assembly (2) is fixedly installed on an inner wall of one side of the outer frame, and the blade guide groove (5) is fixedly installed in parallel on two opposite inner walls of the outer frame (1); the number of the body is at least 2 groups, and the blade telescopic assembly (2) can be adapted to blades (15) of different thicknesses, and any blade (15) can be flexibly selected according to the subdivision scheme to form a combination of various thicknesses and quantities.

[0016] The blade telescopic assembly adopts a parallelogram multi-link structure, is driven by a motor and is driven by a ball screw. The assembly comprises a connecting rod base (6), a limiting shaft sleeve (8), a connecting rod (9), a bearing (10), a screw (11), a coupling (12), a motor (13) and a rotating shaft (14); the connecting rod (9) is a parallelogram multi-link structure formed by hingedly connecting a limiting shaft sleeve (8) and a rotating shaft (14); one end of the connecting rod (9) is fixed on the same side of the connecting rod base (6) and the blade clamping plate (7) and can rotate around the limiting shaft sleeve (8) and the rotating shaft (14); the bearings (10) on the two joints on the other side can roll in the grooves of the connecting rod base (6) and the blade clamping plate (7) under the joint drive of the screw (11), the coupling (12) and the motor (13) respectively, so as to control the telescopic movement of the multi-link and make the blade (15) reciprocate in the blade guide groove (5). This structure has only two positions: fully extended and retracted. It is limited by sensors and completely blocks the beam when fully extended.

[0017] The blade (15) is made of PMMA material.

[0018] The blade guide groove (5) is made of lubricating resin materials such as PMO or nylon, and can also be guided by various methods such as roller groups, bearing groups, guide rods, linear guides, dovetail grooves, synchronous pulleys, etc.

[0019] According to the results of Monte Carlo analysis, a thickness of 36mm is required to block 70MeV energy (corresponding to a tumor depth of 40mm). Through mathematical calculations of the arrangement and combination of slices of different thicknesses, physical calculations, proton beam spot diameter, treatment requirements, engineering difficulty and economy, a thickness segmentation scheme (i.e., the precision of the beam incident depth in the human body) is given, and the thinnest single page is analyzed.

[0020] Embodiment 1:

[0021] The thickness segmentation scheme is determined as 1 mm (the segmentation size corresponding to the beam irradiation depth is approximately 0.9 mm), 2 mm, 4 mm, 8 mm, 16 mm, and the minimum segmentation thickness is 1 mm. With a minimum increment of 1 mm, combinations of 1 mm, 2 mm, 3 mm (2 + 1), 4 mm, 5 mm (4 + 1), 6 mm (4 + 2), 7 mm (4 + 2 + 1), 8 mm, 9 mm (8 + 1), 10 mm (8 + 2), 11 mm (8 + 2 + 1), 12 mm (8 + 4), 13 mm (8 + 4 + 1), 14 mm (8 + 4 + 2), 15 mm (8 + 4 + 3), 16 mm, 17 mm (16 + 1), 18 mm (16 + 2), 19 mm (16 + 2 + 1), 20 mm (16 + 4), 21 mm (16 + 4 + 1), 22 mm (16 + 4 + 2), 23 mm (16 + 4 + 2 + 1), 24 mm (16 + 8), 25 mm (16 + 8 + 1), 26 mm (16 + 8 + 2), 27 mm (16 + 8 + 2 + 1), 28 mm (16 + 8 + 4), 29 mm (16 + 8 + 4 + 1), 30 mm (16 + 8 + 4 + 2), 31 mm (16 + 8 + 4 + 2 + 1), 32 mm (16 + 16), 33 mm (16 + 16 + 1), 34 mm (16 + 16 + 2), 35 mm (16 + 16 + 2 + 1), 36 mm (16 + 16 + 4) can be formed. With a maximum of 5 blades in a group, 36 combinations of blades can be formed, and 6 blades with thicknesses of 1, 2, 4, 8, 16, and 16 mm can be arranged to achieve this.

[0022] Example 2:

[0023] The thickness segmentation scheme is determined as three specifications of 4 mm (the segmentation size corresponding to the beam irradiation depth is approximately 3.6 mm), 8 mm, and 16 mm. Combinations of 4 mm, 8 mm, 12 mm (4 + 8), 16 mm, 20 mm (4 + 16), 24 mm (8 + 16), 28 mm (4 + 8 + 16), 32 mm (8 + 8 + 16), 36 mm (4 + 8 + 8 + 16) can be formed, and 4 blades with thicknesses of 4, 8, 8, and 16 mm can be arranged to achieve this.

[0024] During use, each body is controlled separately. According to different segmentation thicknesses, combinations of blades with different thicknesses are extended to absorb different beam energies, so as to adjust the depth of the beam entering the human body through energy and adapt to tumors at different depths.

[0025] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A multi-leaf preabsorber based on particle flash beam regulation, characterized in that: include: An outer frame (1), a blade guide groove (5), and a body; the body is composed of a blade (15), a blade clamp (7), and a blade telescopic assembly (2); the blade (15) is fixed to one side of the blade clamp (7), and the blade telescopic assembly (2) is installed on the other side of the blade clamp (7); the blade telescopic assembly (2) is fixedly installed on one inner wall of the outer frame, and the blade guide groove (5) is fixedly installed in parallel on two opposite inner walls of the outer frame (1). The number of the main bodies is at least 2 groups, and the blade telescopic assembly (2) can adapt to blades (15) of different thicknesses, and the blades (15) are selected according to a subdivision scheme to form combinations of different thicknesses and quantities.

2. A multi-leaf preabsorber based on particle flash beam regulation according to claim 1, characterized in that: The blade telescopic assembly (2) adopts a parallelogram multi-link structure, is driven by a motor, and is driven by a ball screw.

3. A multi-leaf preabsorber based on particle flash beam regulation according to claim 1 or 2, characterized in that: The blade extension and retraction assembly (2) comprises a connecting rod base (6), a limiting shaft sleeve (8), a connecting rod (9), a bearing (10), a lead screw (11), a coupling (12), a motor (13) and a rotating shaft (14); the connecting rod (9) is a parallelogram multi-link formed by hingedly connecting the limiting shaft sleeve (8) and the rotating shaft (14); one end of the connecting rod (9) is fixed on the same side of the connecting rod base (6) and the blade clamping plate (7) and can rotate around the limiting shaft sleeve (8) and the rotating shaft (14); the bearings (10) on the two joints on the other side can roll in the grooves of the connecting rod base (6) and the blade clamping plate (7) under the joint drive of the lead screw (11), the coupling (12) and the motor (13) respectively, so as to control the extension and retraction of the multi-link and make the blade (15) reciprocate in the blade guide groove (5).

4. The multi-leaf preabsorber based on particle flash beam regulation according to claim 1, characterized in that: The number of the bodies is 6 groups, and the corresponding thicknesses of the blades (15) are 1 mm, 2 mm, 4 mm, 8 mm, 16 mm, and 16 mm.

5. The multi-leaf preabsorber based on particle flash beam regulation according to claim 1, characterized in that: The number of the bodies is 4 groups, and the corresponding thicknesses of the blades (15) are 4 mm, 8 mm, 8 mm, and 16 mm.

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