Shielding device for reducing dark current rays of accelerator

Abstract

The utility model relates to a shielding device for reducing dark current rays of an accelerator, which comprises a stop block arranged in a primary collimator of the accelerator, the stop block is arranged above an ionization chamber of the accelerator and below an accelerating tube, the middle part of one side surface of the stop block is connected with a piston rod, and the piston rod penetrates out of the primary collimator of the accelerator. A pneumatic driving box body is arranged outside the accelerator primary collimator, one end of the piston rod penetrates into the pneumatic driving box body and is connected with a piston, and the pneumatic driving box body is connected with an air compressor through a compressed gas pipeline. A channel for installing the piston rod is arranged in the accelerator primary collimator, a shielding block is arranged in the channel, and the piston rod penetrates through the shielding block. And a pneumatic valve controller is arranged on the compressed gas pipeline. According to the utility model, the output of the dark current can be controlled, the pneumatic driving can realize the rapid switching of the stop blocks, the reliability is high, the redundant space of the dark current of the accelerating tube can be increased, and the situation that the accelerating tube is scrapped due to overhigh dark current is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of medical accelerators of precise radiotherapy equipment, in particular to a shielding device for reducing dark current rays of accelerators. Background Art

[0002] When a medical linear accelerator is working normally, the electron gun introduces electrons into the acceleration cavity. After passing through a series of acceleration cavities, the electrons are focused and accelerated by the electromagnetic field generated by the radio frequency source to form a high-energy electron beam for treatment. "Dark current" means that when the accelerator is not in the beam-emitting state, the electron gun does not actively introduce electrons into the acceleration cavity, but some free electrons still pass through the grid into the acceleration cavity, or free electrons generated by other reasons enter the acceleration cavity. At this time, if the radio frequency source is turned on, the electrons will be accelerated to produce additional high-energy electron beams. This part of the electron beam is called dark current.

[0003] During the treatment process, when the machine works under high voltage, the beam output time accounts for about 40%, and the remaining 60% of the time is in a state where there is no beam output but the RF source is turned on, that is, a dark current is generated. The existence of dark current is obviously redundant and harmful, and to some extent, the target range it affects is uncontrollable, which will impose additional radiation exposure on the patient.

[0004] Accelerator manufacturers will try to limit the level of dark current, but it is currently difficult to completely avoid it from the root cause from a technical point of view. Once the dark current cannot be controlled within an acceptable range, it means that the entire accelerator tube is facing scrapping, which is very costly. Utility Model Content

[0005] The utility model aims to solve the deficiencies of the prior art and provides a shielding device for reducing dark current rays of an accelerator.

[0006] In order to achieve the above-mentioned purpose, the utility model adopts the following technical solutions:

[0007] A shielding device for reducing dark current rays of an accelerator comprises a block installed inside a primary collimator of the accelerator, the block is located above an ionization chamber of the accelerator and below an accelerating tube, a piston rod is connected to the middle of one side of the block, the piston rod passes through the outside of the primary collimator of the accelerator, a pneumatic drive box is arranged outside the primary collimator of the accelerator, one end of the piston rod passes through the inside of the pneumatic drive box and is connected to a piston, and the pneumatic drive box is connected to an air compressor through a compressed gas pipeline.

[0008] A buffer component is arranged on the piston rod, and the buffer component is located between the shielding block and the pneumatic drive box. A stroke in-place switch is installed on the outer wall of the shielding block and the outer wall of the pneumatic drive box at the position where the buffer component contacts.

[0009] A passage for installing a piston rod is arranged in the primary collimator of the accelerator, and a shielding block is arranged in the passage, and the piston rod passes through the shielding block.

[0010] A pneumatic valve controller is provided on the compressed gas pipeline.

[0011] The beneficial effects of the utility model are as follows: the utility model can control the output of dark current, the pneumatic drive can realize the rapid switching of the block, the reliability is high, the redundant space of the dark current of the accelerating tube itself can be increased, and the situation that the accelerating tube is scrapped due to excessive dark current can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a structural schematic diagram of the utility model;

[0013] Figure 2 It is a schematic diagram when the block does not block the electron beam;

[0014] Figure 3 Schematic diagram of the block blocking the electron beam;

[0015] In the figure: 1-block; 2-piston rod; 3-pneumatic drive box; 4-piston; 5-compressed gas pipeline; 6-air compressor; 7-accelerator primary collimator; 8-accelerator ionization chamber; 9-accelerator tube; 10-buffer assembly; 11-shielding block; 12-pneumatic valve controller; 13-support table;

[0016] The following is a detailed description of the embodiments of the present invention with reference to the accompanying drawings. DETAILED DESCRIPTION

[0017] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention. The present invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. The advantages and features of the present invention will become clearer according to the following description. It should be noted that the drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0018] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may also be a component centered. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may also be a component centered. When a component is considered to be "set on" another component, it may be directly set on the other component or there may also be a component centered. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the technical field of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0020] The utility model is further described below in conjunction with the accompanying drawings and embodiments:

[0021] A shielding device for reducing accelerator dark current rays, such as Figures 1 to 3 As shown, it includes a block 1, a piston rod 2, a pneumatic drive box 3, a piston 4, a compressed gas pipeline 5, an air compressor 6, an accelerator primary collimator 7, an accelerator ionization chamber 8, an accelerating tube 9, a buffer assembly 10, a shielding block 11, a pneumatic valve controller 12 and a support platform 13.

[0022] The block 1 is installed inside the primary collimator 7 of the accelerator. The block 1 is located above the ionization chamber 8 of the accelerator and below the accelerating tube 9. A piston rod 2 is connected to the middle of one side of the block 1. The piston rod 2 passes through the outside of the primary collimator 7 of the accelerator. A pneumatic drive box 3 is provided outside the primary collimator 7 of the accelerator. One end of the piston rod 2 passes through the inside of the pneumatic drive box 3 and is connected to a piston 4. The pneumatic drive box 3 is connected to an air compressor 6 through a compressed gas pipeline 5.

[0023] A buffer assembly 10 is provided on the piston rod 2 and is located between the shielding block 11 and the pneumatic drive housing 3. A travel position switch is installed on the outer wall of the shielding block 11 and the outer wall of the pneumatic drive housing 3 at the position in contact with the buffer assembly 10.

[0024] A passage for installing the piston rod 2 is provided in the primary collimator 7 of the accelerator, and a shielding block 11 is provided in the passage, and the piston rod 2 passes through the shielding block 11 .

[0025] A pneumatic valve controller 12 is provided on the compressed gas pipeline 5 .

[0026] A support platform 13 is provided at the bottom of the pneumatic drive box 3 , and the support platform 13 is fixed on the outer wall of the accelerator primary collimator 7 .

[0027] The working principle of the utility model is as follows:

[0028] The accelerator beam state signal (beam on and beam off) is connected to the pneumatic valve controller 12, and the pneumatic valve controller 12 is linked with the beam on / beam off signal.

[0029] When the accelerator enters the beam on state, the pneumatic valve controller 12 drives the block 1 to move to the right, and the beam passes through; when the machine enters the beam off state, the pneumatic valve controller 12 drives the block 1 to move to the left, blocking the beam path and preventing the rays from passing through.

[0030] The size of the stopper 1 is specifically designed according to the energy of the accelerating tube 9 and the beam opening angle.

[0031] Usually, dark current is at the microampere level, and its energy is relatively low. If calculated with reference to 6MV X-rays, the half-value layer thickness of 6MV X-rays is 1.25cm. If the thickness of the block 1 is designed to be 3.75cm, 87.5% of 6MV X-rays can be reduced, which should have a more significant effect on reducing dark current rays. The specific moderate thickness of the block 1 needs to be finally determined through actual testing combined with theoretical calculations.

[0032] The utility model can control the output of dark current, and the pneumatic drive can realize the rapid switching of the block 1, which has high reliability, can increase the redundant space of the dark current of the accelerating tube 9 itself, and reduce the situation that the accelerating tube 9 is scrapped due to excessive dark current.

[0033] The utility model is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the utility model is not limited to the above-mentioned method. As long as various improvements are made using the method concept and technical solution of the utility model, or are directly applied to other occasions without improvement, they are all within the protection scope of the utility model.

Claims

1. A shielding device for reducing accelerator dark current rays, characterized in that: The invention comprises a block (1) installed inside an accelerator primary collimator (7), the block (1) being located above an accelerator ionization chamber (8) and below an accelerating tube (9), a piston rod (2) being connected to the middle of one side of the block (1), the piston rod (2) passing through the outside of the accelerator primary collimator (7), a pneumatic drive box (3) being arranged outside the accelerator primary collimator (7), one end of the piston rod (2) passing through the inside of the pneumatic drive box (3) and being connected to a piston (4), and the pneumatic drive box (3) being connected to an air compressor (6) via a compressed gas pipeline (5).

2. A shielding device for reducing accelerator dark current rays according to claim 1, characterized in that: A buffer assembly (10) is provided on the piston rod (2), and the buffer assembly (10) is located between the shielding block (11) and the pneumatic drive box (3). A stroke position switch is installed on the outer wall of the shielding block (11) and the outer wall of the pneumatic drive box (3) at a position in contact with the buffer assembly (10).

3. A shielding device for reducing accelerator dark current rays according to claim 2, characterized in that: A channel for installing the piston rod (2) is provided in the accelerator primary collimator (7), and a shielding block (11) is provided in the channel, and the piston rod (2) passes through the shielding block (11).

4. A shielding device for reducing accelerator dark current rays according to claim 3, characterized in that: A pneumatic valve controller (12) is provided on the compressed gas pipeline (5).

5. A shielding device for reducing accelerator dark current rays according to claim 4, characterized in that: A support platform (13) is provided at the bottom of the pneumatic drive box (3), and the support platform (13) is fixed on the outer wall of the accelerator primary collimator (7).

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