阅读说明：本技术 一种紧凑型束流图像重现的传输系统 (Compact beam-stream image reproduction transmission system ) 是由 陈伟龙 何源 王志军 黄玉露 马力祯 石健 于 2020-12-30 设计创作，主要内容包括：本发明涉及一种紧凑型束流图像重现的传输系统,包括：第一横向聚焦单元,输入端与漂移管直线加速器输出端连接；第一聚束器,输入端与第一横向聚焦单元输出端连接；第一横向偏转单元,输入端与第一聚束器输出端连接；第二横向聚焦单元,输入端与第一横向偏转单元输出端连接；第二横向偏转单元,输入端与第二横向聚焦单元输出端连接；第二聚束器,输入端与第二横向偏转单元输出端连接；第三横向聚焦单元,连接在第二聚束器和边耦合漂移管直线加速器之间。本发明能够实现传统直线加速器折叠的功能,解决了其占地空间大的问题,为肿瘤治疗医用直线加速器领域提供了设计思路,使肿瘤治疗设备占地更小、成本更低、运维更方便,更利于质子治疗技术的普及和发展。(The invention relates to a compact beam stream image reproduction transmission system, comprising: the input end of the first transverse focusing unit is connected with the output end of the drift tube linear accelerator; the input end of the first beam condenser is connected with the output end of the first transverse focusing unit; the input end of the first transverse deflection unit is connected with the output end of the first beam bunching device; the input end of the second transverse focusing unit is connected with the output end of the first transverse deflection unit; the input end of the second transverse deflection unit is connected with the output end of the second transverse focusing unit; the input end of the second beam condenser is connected with the output end of the second transverse deflection unit; and the third transverse focusing unit is connected between the second beam condenser and the side-coupled drift tube linear accelerator. The folding linear accelerator can realize the folding function of the traditional linear accelerator, solves the problem of large occupied space, provides a design idea for the field of medical linear accelerators for tumor treatment, enables tumor treatment equipment to occupy smaller occupied space, has lower cost and more convenient operation and maintenance, and is more beneficial to popularization and development of proton treatment technology.)

1. A compact beam-stream image reconstruction transmission system, comprising, connected in series by vacuum tubes:

the input end of the first transverse focusing unit (2) is connected with the output end of the drift tube linear accelerator (1) and is used for transverse matching before beam deflection;

the input end of the first beam condenser (3) is connected with the output end of the first transverse focusing unit (1) and is used for longitudinally matching beam current;

a first transverse deflection unit (4), the input end of which is connected with the output end of the first beam condenser (3), and is used for deflecting the beam current by 90 degrees;

the input end of the second transverse focusing unit (5) is connected with the output end of the first transverse deflection unit (4) and is used for transversely matching the beam again;

the second transverse deflection unit (6) is symmetrically arranged with the first transverse deflection unit (4), and the input end of the second transverse deflection unit (6) is connected with the output end of the second transverse focusing unit (5) and is used for deflecting the beam for 90 degrees again;

a second beam splitter (7), the input end of which is connected to the output end of the second transverse deflection unit (6), for beam splitting again in the longitudinal direction;

and the input end of the third transverse focusing unit (8) is connected with the output end of the second beam condenser (7), and the output end of the third transverse focusing unit is connected with the input end of the side-coupled drift tube linear accelerator (9) and is used for transverse matching after beam deflection.

2. The transmission system according to claim 1, characterized in that beam position detectors (10) calibrated to the beam are arranged between the first beam buncher (3) and the first lateral deflection unit (4), between the second lateral deflection unit (6) and the second beam buncher (7) and between the third lateral focusing unit (8) and the side-coupled drift tube linac (9) for beam position and phase information detection; meanwhile, the beam current intensity measurement function is achieved by using a probe of the beam position detector (10) and an analog-digital converter signal of beam induced charge quantity extracted by electronics, and the beam current intensity measurement function is used for realizing non-interception type detection on the transmission efficiency of a transmission system.

3. Transmission system according to claim 1, characterized in that said first transverse focusing unit (2) is at least three first quadrupole lenses (21) arranged side by side and provided with correction coils.

4. A transmission system according to claim 3, characterized in that said second transverse focusing unit (5) is at least three second quadrupole lenses (51) arranged side by side.

5. Transmission system according to claim 4, characterized in that said third transverse focusing unit (8) is at least two third quadrupole lenses (81) arranged side by side and provided with correction coils.

6. The transmission system according to any one of claims 1 to 5, wherein the first (3) and second (7) beamers each employ a beaming cavity with a frequency that is twice the beam frequency and half the frequency of the front and rear accelerating elements.

7. Transport system according to any of claims 1 to 5, characterized in that an emittance meter (12) is detachably fitted downstream of the third transverse focusing unit (8).

8. Transport system according to any of claims 1 to 5, characterized in that the first transverse deflection unit (4) and the second transverse deflection unit (6) each employ 90 ° dipolar magnets with edge angles.

9. The transport system of claim 8, wherein the 90 ° dipole magnet with edge angle has an entrance edge angle in the range of 20 ° to 30 ° and an exit edge angle in the range of 20 ° to 30 °.

Technical Field

The invention relates to a beam transmission system, in particular to a compact beam image reproduction transmission system, and belongs to the technical field of proton treatment.

Background

The medical proton accelerator is widely applied in the international range as tumor treatment equipment, and because the energy deposition of the proton beam has a narrower Bragg peak effect, the proton beam treatment for performing targeted killing on tumor cells is known as the most advanced radiation treatment technology in the world, and compared with the traditional technologies such as X-ray, electronic treatment and the like, the medical proton accelerator can greatly reduce the damage of healthy tissues and organs around tumor focuses.

The current proton treatment accelerator usually adopts a proton cyclotron, a synchrotron or a linear accelerator, and the three accelerators have relatively mature technologies. However, the cyclotron has fixed energy, and the investment of extra energy reduction and adjustment equipment increases the problems of operation difficulty, cost, radiation activation and the like; the beam particle number supplied by the synchrotron is small, the average flow intensity is low, and the occupied area is large; the linear accelerator has the advantages of convenience in injection and extraction and the like, but still has the problems of large occupied space in the beam direction and the like. Therefore, the technical innovation of the compact folded linear accelerator in tumor therapy is the focus research direction in the industry at home and abroad at present.

The compact folding linear accelerator cuts off the linear accelerator from the rear of a certain acceleration section in the middle, realizes deflection in the beam direction through matching of beam transmission lines, and then accelerates with higher energy, thereby reducing the occupied space. However, the main difficulties of the deflection type beam transmission line include: firstly, an accelerator is cut off between certain acceleration sections and a deflection transmission line is designed, which means that image reconstruction needs to be realized according to matching parameters of transmission line inlet and outlet beams, the requirement on flow mechanics design of transmission line beams is high, and the transmission line is required to have high matching capacity; if the de-dispersion structure is not designed in the deflection section, the quality of the downstream beam is deteriorated, and the beam loss probability of the deflection section is increased; the realization of the deflection section needs a plurality of dipolar magnets and quadrupole magnets, a correcting magnet, a beam bunching device and corresponding beam diagnosis elements to ensure beam transmission matching, thus increasing the debugging difficulty; and fourthly, the longitudinal phase width of the beam is increased due to the overlong design of the transverse focusing section, so that the longitudinal matching difficulty with a downstream accelerator is increased.

Disclosure of Invention

In view of the above problems, an object of the present invention is to provide a compact beam image reconstruction transmission system, so as to solve the problem of large occupied space in the beam direction of the conventional linear accelerator.

In order to achieve the purpose, the invention adopts the following technical scheme: a compact beam-stream image reconstruction transport system comprising, connected in series by vacuum tubes: the input end of the first transverse focusing unit is connected with the output end of the drift tube linear accelerator and is used for transverse matching before beam deflection; the input end of the first beam condenser is connected with the output end of the first transverse focusing unit and is used for longitudinally matching beam current; the input end of the first transverse deflection unit is connected with the output end of the first beam condenser and is used for deflecting the beam current by 90 degrees; the input end of the second transverse focusing unit is connected with the output end of the first transverse deflection unit and is used for transversely matching the beam again; the second transverse deflection unit is symmetrically arranged with the first transverse deflection unit, and the input end of the second transverse deflection unit is connected with the output end of the second transverse focusing unit and used for deflecting the beam for 90 degrees again; the input end of the second beam condenser is connected with the output end of the second transverse deflection unit and is used for longitudinally matching the beam again; and the input end of the third transverse focusing unit is connected with the output end of the second beam condenser, and the output end of the third transverse focusing unit is connected with the input end of the side-coupled drift tube linear accelerator and used for transverse matching after beam deflection.

In the transmission system, preferably, beam position detectors calibrated by beams are arranged between the first beam condenser and the first transverse deflection unit, between the second transverse deflection unit and the second beam condenser, and between the third transverse focusing unit and the side-coupled drift tube linear accelerator, and are used for detecting beam position and phase information; meanwhile, the beam current intensity measurement function is achieved by using a probe of the beam position detector and an analog-digital converter signal of beam induced charge quantity extracted by electronics, and the beam current intensity measurement function is used for realizing non-interception type detection on the transmission efficiency of a transmission system.

The transmission system, preferably, the first transversal focusing unit is at least three first quadrupole lenses arranged side by side and provided with a correction coil.

In the transmission system, preferably, the second transversal focusing unit is at least three second quadrupole lenses arranged side by side.

The transmission system, preferably, the third transversal focusing unit is at least two third quadrupole lenses arranged side by side and provided with a correction coil.

In the transmission system, preferably, the first and second bunchers both use a bunching cavity with frequency of twice the beam frequency and half the frequency of the front and rear accelerating units.

The transport system is preferably detachably equipped with an emittance meter downstream of the third transverse focusing unit.

In the transport system, the first transverse deflection unit and the second transverse deflection unit both use 90 ° dipolar magnets with edge angles.

Preferably, the entrance edge angle of the 90 ° dipolar magnet with an edge angle is designed to be in a range of 20 ° to 30 °, and the exit edge angle is designed to be in a range of 20 ° to 30 °.

Due to the adoption of the technical scheme, the invention has the following advantages: 1. the invention adopts 2 90-degree dipolar magnets to form a beam transmission system with a 180-degree deflection section design, the deflection section can realize the folding function of the traditional linear accelerator, can effectively compress the occupied space of the deflection section, solves the problem of large occupied space of the traditional linear accelerator, provides a design idea for the field of medical linear accelerators for tumor treatment, and ensures that tumor treatment equipment has smaller occupied space, lower cost and more convenient operation and maintenance, thereby being more beneficial to the popularization and development of proton treatment technology. 2. The cavity with frequency of twice frequency of beam frequency and half frequency of front and back accelerating units is used as a longitudinal beam buncher, matching of transverse and longitudinal beam parameters between upstream and downstream accelerating sections of a transmission line is realized, and beam matching and achromatic beam transmission are realized by the aid of a combined quadrupole lens.

Drawings

FIG. 1 is a schematic layout of the present invention;

FIG. 2 is a plot of the dynamic 3RMS envelope of the deflection section of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "upper", "lower", "lateral", "longitudinal", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the system or element referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like are used to define elements only for convenience in distinguishing between the elements, and if not otherwise stated, are not to be construed as indicating or implying any relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

As shown in fig. 1, the compact beam stream image reproduction transmission system provided by the present invention comprises: the input end of the first transverse focusing unit 2 is connected with the output end of a Drift Tube linear accelerator 1 (DTL), and the first transverse focusing unit is used for transverse matching before beam deflection so as to realize strong focusing of the beam and keep better beam quality; the input end of the first beam condenser 3 is connected with the output end of the first transverse focusing unit 1 and is used for longitudinally matching beam current; a first transverse deflection unit 4, the input end of which is connected with the output end of the first beam buncher 3, and is used for deflecting the beam current by 90 degrees; the input end of the second transverse focusing unit 5 is connected with the output end of the first transverse deflection unit 4 and is used for secondary transverse matching of the beam, so that the first transverse deflection unit 4 is assisted to realize the function of achromatization, the sensitivity of the transmission line to beam energy jitter and energy dispersion is improved, the probability of beam loss in the transmission line is reduced, and the quality of the beam entering a downstream accelerator is improved; the second transverse deflection unit 6 is symmetrically arranged with the first transverse deflection unit 4, and the input end of the second transverse deflection unit 6 is connected with the output end of the second transverse focusing unit 5 and used for deflecting the beam for 90 degrees again; the input end of the second beam buncher 7 is connected with the output end of the second transverse deflection unit 6 and used for longitudinally matching the beam again so that the beam can meet the beam bunching structure requirement of a downstream accelerator; an input end of the third transverse focusing unit 8 is connected with an output end of the second beam condenser 7, and an output end of the third transverse focusing unit is connected with an input end of a Side Coupling Drift Tube linear accelerator 9 (SCDTL) for transverse matching after beam deflection, so that strong focusing of beam is realized, and better beam quality is maintained.

In the above embodiment, preferably, Beam Position detectors 10(Beam Position detectors, BPMs) calibrated by beams are respectively disposed between the first Beam condenser 3 and the first transverse deflection unit 4, between the second transverse deflection unit 6 and the second Beam condenser 7, and between the third transverse focusing unit 8 and the side-coupled drift tube linac 9, and are used for detecting Beam Position and phase information, so as to perform trajectory correction in Beam debugging and Beam energy test based on Time of flight (TOF); meanwhile, the probe of the BPM10 and ADC signals (analog-digital converter signals) of beam induced charge quantity extracted by electronics can have the beam current intensity measurement function, so that the transmission efficiency of the transmission system can be detected in a non-interception mode by using the BPM 10. It should be emphasized that, in this embodiment, the front and the back of the transmission line are acceleration units (DTL1 and SCDTL9), and the BPM10 needs to detect the beam phase while detecting the beam position, that is, has a beam energy calibration function, and is an indispensable beam diagnosis element for calibrating the cavity pressure and the phase of the beam condenser.

In the above embodiment, preferably, beam intensity detectors 11(AC Current transformers, ACCTs) are disposed at positions close to the output end of the drift tube linear accelerator 1 and at positions close to the input end of the side-coupled drift tube linear accelerator 9, and are used for detecting the average beam intensity, so that on one hand, the transmission efficiency of the transmission line can be monitored, and on the other hand, beam particle counting can be provided for the therapy terminal.

In the above embodiment, preferably, the first transversal focusing unit 2 is at least three quadrupole lenses 21 arranged side by side and having correction coils, the third transversal focusing unit 8 is at least two quadrupole lenses 81 arranged side by side and having correction coils, and the quadrupole magnets are combined with the correction coils, so that on one hand, orbit correction in beam current debugging can be realized, and on the other hand, the occupied space of the correction coils can be saved; the second transversal focusing unit 5 is at least three quadrupole lenses 51 arranged side by side.

In the above embodiment, preferably, because the longitudinal beam output by the upstream accelerator has a small phase width, the beam focusing capacity of the beam focusing cavity with the same frequency (beam frequency of 750MHz) is weak, and in order to complete the dynamic design (i.e., beam image reproduction) that the beam distribution at the inlet and the outlet is completely consistent, the first beam condenser 3 and the second beam condenser 7 both use the beam focusing cavity with the frequency of 750MHz, which is double frequency and half frequency of the front and rear acceleration units (DTL1 and SCDTL9), which can effectively reduce the cavity voltage, improve the cavity utilization rate, shorten the transmission line length, and realize the longitudinal beam matching of the upstream accelerator and the downstream accelerator.

In the above embodiment, preferably, in order to ensure that the beam current can meet the requirement, the emittance measuring instrument 12 is detachably mounted downstream of the third transverse focusing unit 8, so as to measure the beam current parameter and ensure that the beam current entering the downstream accelerator meets the requirement of image reproduction.

In the above embodiment, preferably, the first transverse deflection unit 4 and the second transverse deflection unit 6 both use 90 ° dipolar magnets with edge angles, where the edge angles are designed mainly to compensate focusing factors in the transverse direction, to implement smooth transverse beam matching, to reduce emittance increase caused by beam envelope oscillation, and to reduce cost increase caused by dynamic compensation by additional quadrupole magnets and to save floor space.

In the above embodiment, preferably, the design range of the entrance edge angle of the 90 ° dipole magnet with the edge angle is 20 ° to 30 °, and the design range of the exit edge angle is 20 ° to 30 °, so that when the edge angle is designed to cooperate with the quadrupole magnet 51 to achieve beam dispersion elimination, the beam sizes in the dipole magnets 4 and 6 and between the dipole magnets 4 and 6 can be effectively controlled, the beam loss is reduced, and the beam transmission efficiency is improved.

In the above embodiment, preferably, the above components are connected by a vacuum pipe, and are used for vacuum maintenance in the beam transmission process, so as to ensure that the beam is not scattered or lost.

Fig. 2 shows a deflection section dynamics 3RMS envelope diagram obtained by performing simulation analysis on the compact beam image reproduction transmission system of the present invention, where the upper diagram is a beam envelope diagram in the horizontal/vertical direction of the beam, the middle diagram is a dispersion function envelope diagram, and the lower diagram is a phase width envelope diagram, as can be seen from the diagram, the maximum dispersion function in the matching section is 1400mm, and the dispersion function after the deflection section passes through the dipole magnet is 0, so that achromatic dispersion is realized, and the matching requirement of the downstream accelerator can be satisfied.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.