A beam focusing and transmission system applied to an ultra-high energy electron beam and a radiotherapy device

Abstract

The present disclosure relates to a beam focusing transmission system applied to an ultra-high energy electron beam and a radiotherapy device, the system comprising: a transmission module and a focusing module, the quadrupole iron in the transmission module is used to diverge the incoming electron beam in the focusing exit direction and focus the incoming electron beam in the parallel exit direction; the deflection dipole iron in the transmission module is used to deflect the incoming electron beam by a specified angle in the parallel exit direction; the focusing module is used to focus the electron beam emitted by the transmission module in the focusing exit direction and diverge the electron beam emitted by the transmission module in the parallel exit direction, and different electrons in the electron beam emitted by the focusing module enter the target object at different positions and focus on the target region in the target object. According to the system of the embodiment of the present disclosure, the electron beam can be flattened and focused to increase the dose deposition peak depth in the target object, and the compactness of the whole beam focusing transmission system is improved.

Description

[0001] This disclosure claims priority to Chinese Patent Application No. 202211461413.0, filed on November 21, 2022, entitled “Electron Beam Focusing System and Radiotherapy Device”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to the field of electron beam processing, and more particularly to a beam focusing and transmission system and radiotherapy equipment for use with ultra-high energy electron beams. Background Technology

[0003] Radiotherapy utilizes high-energy ionizing radiation to destroy the biochemical structure of cancer cells, thereby inhibiting tumor growth. Currently, radiotherapy primarily uses electron, photon, and proton beams. Traditional electron radiotherapy mainly employs low-energy electron beams in the energy range of 6 MeV to 20 MeV. Due to its shallow penetration depth and poor lateral penumbra quality, it is only suitable for treating superficial tumors (within 5 cm of the body), such as those in the skin and limbs, and cannot be used for radiotherapy of deep tumors. In recent years, with the development of new electron accelerator technologies such as laser plasma wakewave acceleration, it has become possible to use ultra-high-energy electron beams (electron beams in the energy range of 50 MeV to 250 MeV) for radiotherapy of deep tumors.

[0004] However, when ultra-high energy electron beams are injected directly and parallel into the human body, they will form high dose deposits at the entrance and exit of the body, making it difficult to form dose peaks in the deep lesion areas of the body. This will reduce the effectiveness of electron radiotherapy. Moreover, miniaturized radiotherapy equipment is becoming a development trend. Therefore, in order to enable ultra-high energy electron beams to form dose peaks in the deep lesion areas of the human body and adapt to miniaturized radiotherapy equipment, it is necessary to design a beam focusing and transmission system with strong focusing capabilities and a compact structure. Summary of the Invention

[0005] In view of this, this disclosure proposes a beam focusing and transmission system and radiotherapy equipment for use with ultra-high energy electron beams. This system can not only reduce the dose deposition formed by the ultra-high energy electron beam at the entrance and exit of the human body, but also enable the ultra-high energy electron beam to form a dose peak in the deep lesion area of ​​the human body, thereby improving the effect of electron radiotherapy and improving the compactness of the entire system. This makes it more suitable for miniaturized radiotherapy equipment and helps to reduce the spatial scale of the entire radiotherapy equipment.

[0006] According to one aspect of this disclosure, a beam focusing and transmission system for ultra-high energy electron beams is provided, comprising: a transmission module and a focusing module, wherein an electron beam to be focused sequentially enters the transmission module and the focusing module; the transmission module includes at least one quadrupole and a deflecting dipole; each quadrupole in the transmission module is used to diverge the incoming electron beam in the focusing exit direction and focus the incoming electron beam in the parallel exit direction, so that the electron beam emitted by the transmission module is an electron beam that diverges in the focusing exit direction and is focused in the parallel exit direction; wherein the focusing exit direction is parallel to the magnetic field direction of the deflecting dipole, and the parallel exit direction is perpendicular to the magnetic field direction of the deflecting dipole; the deflecting dipole in the transmission module... Diodes are used to deflect the incoming electron beam by a specified angle in the parallel emission direction to change the transmission direction of the incoming electron beam. The transmission direction of the electron beam emitted by the transmission module is different from the transmission direction of the electron beam before entering the transmission module. The focusing module includes a quadrupole, which is used to focus the electron beam emitted by the transmission module in the focusing emission direction and to diverge the electron beam emitted by the transmission module in the parallel emission direction, so that the electron beam emitted by the focusing module is a focused electron beam emitted in the focusing emission direction and a near-parallel electron beam emitted in the parallel emission direction. Different electrons in the electron beam emitted by the focusing module are used to enter the target object at different positions and focus on the target area within the target object.

[0007] In one possible implementation, the system further includes a control module electrically connected to the quadrupole in the transmission module, the deflecting diode, and the quadrupole in the focusing module. The control module is configured to control the quadrupole in the transmission module, the deflecting diode, and the quadrupole in the focusing module to generate magnetic induction intensities matching the target area, based on the focusing depth corresponding to the target area and the initial beam parameters of the electron beam to be focused, so that the electron beam emitted by the focusing module is focused onto the target area. The initial beam parameters include at least one of the following: electron energy, divergence angle, and beam spot size.

[0008] In one possible implementation, by controlling the deflecting diode to generate a magnetic induction intensity matching the target area, energy selection of electrons of different energies in the incoming electron beam is achieved; by controlling the quadrupole in the transmission module and the quadrupole in the focusing module to generate magnetic induction intensities matching the target area, the incident position and incident angle of different electrons in the electron beam emitted by the focusing module when entering the target object, as well as the focusing depth after entering the target object, are controlled.

[0009] In one possible implementation, the specified angle includes any angle between 30 and 150 degrees.

[0010] In one possible implementation, when the transmission module includes at least two quadrupoles, the deflecting diodes in the transmission module are located between any pair of adjacent quadrupoles in the transmission module, or before or after at least two quadrupoles in the transmission module.

[0011] In one possible implementation, the transmission module and the focusing module are disposed outside the beam transmission channel of the electron beam, wherein the beam transmission channel has a rotation angle at the deflecting diode that is the same as the specified angle.

[0012] In one possible implementation, the electron beam comprises an ultra-high energy electron beam with a voltage of 50 MeV to 250 MeV generated by an ultra-high energy electron source.

[0013] According to another aspect of this disclosure, a radiotherapy device is provided, comprising: an ultra-high energy electron source for generating an electron beam; and the aforementioned beam focusing and transmission system.

[0014] In one possible implementation, the beam focusing and transmission system is disposed in the robotic arm of the radiotherapy device, the robotic arm being rotatable around the target object.

[0015] According to embodiments of this disclosure, the electron beam is diverged in the focusing direction and focused in the parallel direction by a quadrupole in the transmission module. Furthermore, the quadrupole in the focusing module transforms the divergent electron beam emitted from the transmission module into a strongly focused beam in the focusing direction and a parallel beam in the parallel direction. This allows the electron beam emitted from the focusing module to be focused at a large angle and flatly onto the target area of ​​the target object (e.g., a lesion area inside a patient's body). Since different electrons in the electron beam emitted from the focusing module enter the target object at different positions and focus on the target area within the target object, dose deposition at the target object's inlet / outlet can be reduced, achieving a peak dose deposition in the target area. This significantly reduces the radiation dose to other normal tissues within the target object, improving the effectiveness of electron radiotherapy. Simultaneously, by utilizing deflecting dipoles, the electron beam can be deflected at a specified angle, allowing the entire beam focusing transmission system to be folded in space, making the entire beam focusing transmission system more compact and suitable for miniaturized radiotherapy equipment.

[0016] Other features and aspects of this disclosure will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0017] The accompanying drawings, which are included in and form part of this specification, illustrate exemplary embodiments, features, and aspects of this disclosure together with the specification and serve to explain the principles of this disclosure.

[0018] Figure 1 A schematic diagram showing a comparison of the peak dose of a parallel beam and a focused beam according to an embodiment of the present disclosure is provided.

[0019] Figure 2 A schematic diagram of a beam focusing and transmission system according to an embodiment of the present disclosure is shown.

[0020] Figure 3 A schematic diagram of a beam focusing and transmission system according to an embodiment of the present disclosure is shown.

[0021] Figure 4a and Figure 4b A schematic diagram showing the trajectory of an electron beam according to an embodiment of the present disclosure is provided.

[0022] Figure 5 A schematic diagram of a beam focusing and transmission system according to an embodiment of the present disclosure is shown.

[0023] Figure 6a , Figure 6b and Figure 6c This diagram illustrates the dose distribution of an electron beam deposited in water according to an embodiment of the present disclosure. Detailed Implementation

[0024] Various exemplary embodiments, features, and aspects of this disclosure will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0025] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0026] Furthermore, to better illustrate this disclosure, numerous specific details are set forth in the following detailed description. Those skilled in the art will understand that this disclosure can be practiced without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art have not been described in detail in order to highlight the main points of this disclosure.

[0027] Radiation therapy uses high-energy ionizing radiation such as X-rays, gamma rays, electrons, and protons to destroy the biochemical structure of cancer cells, thereby inhibiting tumor growth. Because this radiation also damages normal tissue cells, a specific treatment plan needs to be developed to minimize the side effects on normal tissues.

[0028] Currently, clinical radiotherapy primarily uses photons, protons, or electrons for irradiation. The most widely used technique is the photon approach, which is cost-effective and efficient, but has limitations in terms of dose deposition in organs at risk and radiobiological effects. The proton / heavy ion approach offers superior dose distribution, but its construction costs are too high and its treatment efficiency is low, with a treatment center only able to treat about 1,000 patients per year. Traditional electron beam radiotherapy mainly uses low-energy electron beams in the 6MeV-20MeV range output from radiofrequency linear accelerators. Insufficient maximum penetration depth and poor transverse penumbra quality limit the application of these techniques in actual treatment, especially in deep tumor radiotherapy.

[0029] Ultra-high-energy electron beams (50MeV-250MeV) overcome the aforementioned drawbacks of low-energy electron beams, enabling deeper dose deposition and sharper lateral penumbra. Recent Monte Carlo simulations have compared the therapeutic effects of photons, protons, and ultra-high-energy electrons via intensity-modulated radiotherapy (IMRT) on tumors such as those in the prostate and brain. Studies have found that ultra-high-energy electron beams are significantly more effective than photon beams, but slightly less effective than proton beams. Considering that the construction cost of electron accelerators is generally much lower than that of proton accelerators, radiotherapy devices based on ultra-high-energy electron beams have significant potential market value. In recent years, novel electron accelerator technologies such as laser plasma wakewaves and X-band linear electron accelerators have further reduced the scale of accelerators to the desktop level, making the advantages of ultra-high-energy electron radiotherapy even more pronounced.

[0030] Although ultra-high energy electron beam radiotherapy has certain advantages over X-ray technology, it still produces a high dose deposition on the human body surface and other normal tissue areas, thus posing a certain risk of radiation toxicity. Figure 1 As shown, parallel beams (i.e., parallel incident ultra-high energy electron beams) have difficulty forming dose deposition peaks at deeper target depths, which is not advantageous for treating deep tumors located between 10cm and 20cm in the body. In contrast, focused beams (i.e., focused incident ultra-high energy electron beams) can form better dose deposition peaks at the target depth. Therefore, it is essential to design a beam focusing and delivery system that can strongly focus ultra-high energy electron beams to deep lesion areas. On this basis, it is also essential to further improve the high compactness of the beam focusing and delivery system to achieve adaptation to miniaturized electron radiotherapy equipment.

[0031] In view of this, the present disclosure provides a beam focusing and transmission system for ultra-high energy electron beams, which can be applied to radiotherapy equipment using ultra-high energy electron beams. It is suitable for radiotherapy of tumors in the human body, especially deep tumors, and can further reduce the spatial scale of radiotherapy equipment while ensuring that the ultra-high energy electron beam achieves peak dose deposition in deep tumor regions.

[0032] The following is combined Figures 2 to 5 The beam focusing and transmission system provided in the embodiments of this disclosure will be described in detail.

[0033] Figure 2 A schematic diagram of a beam focusing and delivery system according to an embodiment of the present disclosure is shown. This beam focusing and delivery system can be applied to various electron radiotherapy devices, such as radiotherapy devices employing ultra-high-energy electron beams. Figure 2 As shown, the beam focusing and transmission system includes a transmission module 201 and a focusing module 202, wherein the electron beam to be focused enters the transmission module 201 and the focusing module 202 in sequence.

[0034] The transmission module 201 includes at least one quadrupole and a deflecting diode; each quadrupole in the transmission module is used to diverge the incoming electron beam in the focusing emission direction and focus the incoming electron beam in the parallel emission direction, so that the electron beam emitted by the transmission module 201 is an electron beam that diverges in the focusing emission direction and is focused in the parallel emission direction; wherein, the focusing emission direction is parallel to the magnetic field direction of the deflecting diode, and the parallel emission direction is perpendicular to the magnetic field direction of the deflecting diode.

[0035] The deflecting diode in the transmission module 201 is used to deflect the incoming electron beam by a specified angle in the parallel emission direction, so as to change the transmission direction of the incoming electron beam. The transmission direction of the electron beam emitted from the transmission module is different from the transmission direction of the electron beam before entering the transmission module.

[0036] The focusing module 202 includes a quadrupole. The quadrupole in the focusing module is used to focus the electron beam emitted by the transmission module in the focusing emission direction and to diverge the electron beam emitted by the transmission module in the parallel emission direction, so that the electron beam emitted by the focusing module 202 is an electron beam that is focused and emitted in the focusing emission direction and nearly parallel emitted in the parallel emission direction. Different electrons in the electron beam emitted by the focusing module 202 are used to enter the target object at different positions and focus on the target area within the target object.

[0037] The electron beam entering the aforementioned beam focusing and transmission system can be an ultra-high-energy electron beam with a voltage of 50 MeV-250 MeV generated by an ultra-high-energy electron source. The ultra-high-energy electron source can include accelerators such as laser plasma accelerators and high-gradient electron linear accelerators; this disclosure does not limit the type of ultra-high-energy electron source. It is understood that when an ultra-high-energy electron beam generated by an ultra-high-energy electron source propagates through matter, it diverges in a pencil-shaped beam due to scattering. If all electrons in the electron beam enter the lesion area of ​​the human body along the same trajectory (i.e., at the same position and angle), it will cause excessively high radiation doses to be deposited on the surface of the human skin (i.e., the entrance and exit point of the human body). To obtain a peak dose deposition in a deeper lesion area, it is necessary to have different electrons in the electron beam enter the human body at different positions and focus on the lesion area. This disclosure embodiment can emit an electron beam in a flat, high-focusing manner, achieving peak dose deposition in a deeper location within the human body.

[0038] By diverging and then refocusing the electron beam in the focused emission direction, and simultaneously focusing and then diverging in the parallel emission direction, different electrons in the emitted electron beam can enter the human body at different locations, forming a dose deposition peak in the lesion area, which is beneficial to improving the effect of electron radiotherapy. Here, dose represents the energy delivered by electron radiation to a unit mass of matter; the target object can be understood as the object to be radiotreated, such as a human or animal; and the target area can be understood as the target region to be radiotreated, such as the lesion area where a tumor is located in the human body.

[0039] It is known that, since the magnetic field distribution of a single quadrupole iron will simultaneously produce focusing and defocusing effects on the electron beam, and the focusing and defocusing effects on the electron beam in the magnetic field are opposite in direction, it is difficult to achieve strong focusing in both directions simultaneously within a certain transmission distance. Therefore, the embodiments of this disclosure adopt a "flat focusing" method that achieves strong focusing in the focusing emission direction and approximately parallel emission in the parallel emission direction.

[0040] In practical applications, the magnetic field direction of the deflecting dipole in the transmission module 201 can be preset. Since the focusing exit direction is parallel to the magnetic field direction of the deflecting dipole, and the parallel exit direction is perpendicular to the magnetic field direction of the deflecting dipole, the focusing exit direction and the parallel exit direction are also known and fixed after the magnetic field direction of the deflecting dipole is fixed. Consequently, the polarity of the quadrupole in the transmission module 201 and the focusing module 202 is also known and fixed. The polarity of the quadrupole can include the focusing direction with focusing effect and the defocusing direction with defocusing effect. The magnetic field direction of the deflecting dipole is perpendicular to the parallel exit direction and parallel to the focusing exit direction (that is, consistent with the lateral focusing direction of the beam). This can avoid the divergent beam generated by the defocusing effect of the quadrupole in the focusing exit direction from having different propagation trajectories in the deflecting dipole, thus ensuring that the divergent beam has the same propagation trajectory in the deflecting dipole.

[0041] Optionally, the polarities of the quadrupoles in the transmission module 201 can be consistent, while the polarities of the quadrupoles in the focusing module 202 can be opposite to those in the transmission module 201. The consistent polarity of the quadrupoles in the transmission module 201 means that each quadrupole in the transmission module 201 defocuses the electron beam in the focusing emission direction and focuses it in the parallel emission direction. Conversely, the opposite polarity of the quadrupoles in the focusing module 202 means that the quadrupoles in the focusing module 202 focus the electron beam in the focusing emission direction and defocus it in the parallel emission direction. Thus, the electron beam emitted by the system is a strongly focused beam in the focusing emission direction and a parallel-emission beam in the parallel emission direction.

[0042] Optionally, when the transmission module 201 contains two or more quadrupoles, quadrupoles with opposite polarities may also exist in the transmission module 201. That is, the transmission module 201 may include some quadrupoles that defocus the electron beam in the focusing emission direction and focus the electron beam in the parallel emission direction, and some quadrupoles that focus the electron beam in the focusing emission direction and defocus the electron beam in the parallel emission direction. As long as the electron beam emitted by the transmission module 201 is ensured to be a divergent electron beam in the focusing emission direction and a focused electron beam in the parallel emission direction, this embodiment of the present disclosure does not impose any limitations on this.

[0043] For example, such as Figure 3The beam focusing and transmission system shown includes a transmission module 201 comprising a quadrupole 2011, a deflecting diode 2012, and a quadrupole 2013; and a focusing module 202 comprising a quadrupole 2021. The quadrupole 2011 diverges the incoming electron beam in the focusing exit direction and focuses the incoming electron beam in the parallel exit direction. The deflecting diode 2012 deflects the electron beam emitted from the quadrupole 2011 by a specified angle α, thus changing the transmission direction of the electron beam. The specified angle can be any angle between 30 degrees and 150 degrees. The quadrupole 2013 further diverges the electron beam emitted from the deflecting diode 2012 in the focusing exit direction and focuses it in the parallel exit direction. The electron beam emitted by the deflecting diode 2012 is further focused in the emission direction; the quadrupole 2021 in the focusing module 202 focuses the electron beam emitted by the quadrupole 2013 in the focused emission direction and diverges the electron beam emitted by the quadrupole 2013 in the parallel emission direction. Thus, the electron beam emitted by the quadrupole 2021 is an electron beam that is focused in the focused emission direction and parallel in the parallel emission direction. Different electrons in the electron beam emitted by the quadrupole 2021 will enter the target object at different positions and be focused on the target area within the target object, thereby achieving large-angle flat focusing on the target area and realizing radiation dose deposition in the target area.

[0044] Among them, Figure 3 In the beam focusing transmission system shown, the quadrupole 2011 in the focusing exit direction diverges the electron beam from an approximately pencil-shaped beam into a divergent beam. The quadrupole 2013 further diverges the electron beam in the focusing exit direction. By the time it reaches the quadrupole 2021, after the divergence of the quadrupoles 2011 and 2013, the divergence scale and beam size of the electron beam in the focusing exit direction are already very large. The quadrupole 2021 then focuses the divergent electron beam onto the target area at a large angle. In the parallel exit direction, the quadrupole... The quadrupole 2011 and quadrupole 2013 focus the electron beam with an initial divergence angle into a smaller beam spot. Then, through the defocusing effect of the quadrupole 2021, the electron beam achieves near-parallel emission in the parallel emission direction. A deflecting diode 2012 is set in the gap between the quadrupole 2011 and quadrupole 2013, so that the electron beam is deflected by a specified angle α (e.g., α=90 degrees), thereby making the transmission direction of the electron beam spatially folded. This is beneficial for making the beam focusing and transmission system more compact by achieving spatial folding.

[0045] For example, based on Figure 3 The beam focusing and transmission system shown is Figure 4a The diagram shows the electron beam trajectory of the beam focusing and transmission system in the focusing and emission direction. Figure 4bThe electron beam trajectory of the beam focusing and transmission system in the parallel emission direction is shown, as follows: Figure 4a As shown, in the focusing exit direction, tetrapole 2011 and tetrapole 2013 have a defocusing effect on the electron beam, while tetrapole 2021 has a focusing effect. That is, the electron beam gradually diverges after passing through tetrapole 2011 and tetrapole 2013, and is focused after passing through tetrapole 2021. Figure 4b As shown, in the parallel emission direction, quadrupole 2011 and quadrupole 2013 focus the electron beam, while quadrupole 2021 defocuses it. It should be understood that because the combined focusing effect of quadrupole 2011 and quadrupole 2013 on the electron beam is strong in the parallel emission direction, the defocusing effect of quadrupole 2021 only partially offsets the combined focusing effect of quadrupole 2011 and quadrupole 2013. This results in the electron beam emitted by quadrupole 2021 having a near-parallel emission effect in the parallel emission direction, or in other words, the divergence angle in the parallel emission direction is not very large.

[0046] In this context, divergent emission can be understood as electrons in an electron beam being emitted in a divergent manner, or in other words, the trajectories of electrons in a divergent emission electron beam are divergent, for example... Figure 4a The electron beams emitted by the 2011 and 2013 quadrupole electron beams; focused emission can be understood as the electrons in the electron beam being emitted with a focused effect, or in other words, the trajectory of the electrons in the focused emission electron beam is focused, for example... Figure 4a The parallel emission of the electron beam emitted by the quadrupole 2021 can be understood as the electrons in the electron beam maintaining a parallel effect when emitted, or in other words, the trajectories of the electrons in the parallel-emitted electron beam are parallel to each other.

[0047] It should be understood that, Figure 3 The beam focusing transmission system shown is one possible implementation provided by the embodiments of this disclosure, and does not represent all implementations of the embodiments of this disclosure. In fact, those skilled in the art can customize the design of the number of quadrupoles in the transmission module 201, the position of the deflecting dipoles in the transmission module 201, and the specified angle of deflection of the deflecting dipoles according to actual needs (such as the hardware structure of the radiotherapy equipment, the spatial dimensions of the quadrupoles and dipoles, etc.). The embodiments of this application do not limit this.

[0048] For example, if the transmission module 201 includes a quadrupole, the deflecting diode can be located after the quadrupole. If the transmission module 202 includes two quadrupoles, the deflecting diode can be located between the two quadrupoles, or after or before the two quadrupoles. If the transmission module 201 includes three quadrupoles, the deflecting diode can be located after the first two quadrupoles, after the first quadrupole, or after all three quadrupoles. That is, when the transmission module includes at least two quadrupoles, the deflecting diode in the transmission module can be located between any pair of adjacent quadrupoles in the transmission module, or it can be located after at least two quadrupoles in the transmission module, or it can be located before at least two quadrupoles in the transmission module.

[0049] It should be understood that the deflection angle that the deflecting diode can deflect can include any angle from 30 degrees to 150 degrees. Specifically, it can include custom angles such as 90 degrees, 80 degrees, and 95 degrees, depending on the overall hardware structure of the beam focusing system. However, regardless of the deflection angle of the deflecting diode, the focusing module 202 should be located in the transmission direction of the electron beam emitted by the transmission module 201. The transmission direction of the electron beam can be understood as the overall trajectory of the electron beam in the system, for example... Figure 3 The electron beam shown is transverse before passing through the deflector diode 2012, and its direction of propagation becomes longitudinal before passing through the deflector diode 2012.

[0050] It is known that electron beams are typically transmitted within a beam transmission channel, which can be, for example, a vacuum-sealed channel. The transmission module 201 and focusing module 202 can be located outside the electron beam transmission channel. That is, the quadrupole and deflecting diode in the transmission module 201, and the quadrupole in the focusing module 202, are all located outside the electron beam transmission channel. Since the deflecting diode can deflect the transmission direction of the electron beam by a specified angle, the beam transmission channel has a rotation angle equal to the specified angle at the deflecting diode location. For example… Figure 3 The thick solid lines passing through quadrupole 2011, deflecting diode 2012, quadrupole 2013, and quadrupole 2021 represent the beam transmission channel, which has a specified 90° turn at deflecting diode 2012. It should be understood that this disclosure does not limit the arrangement of the transmission module 201 and focusing module 202 outside the beam transmission channel.

[0051] In this system, the quadrupole iron in the transmission module 201, the deflecting dipolar iron, and the quadrupole iron in the focusing module 202 can all be electromagnets. Therefore, the magnitude of the magnetic induction intensity of each quadrupole iron and the deflecting dipolar iron can be controlled by controlling the magnitude of the current flowing through each quadrupole iron in the transmission module 201, the deflecting dipolar iron, and the quadrupole iron in the focusing module 202. Furthermore, the polarity (or magnetic field direction) of each quadrupole iron and the magnetic field direction of the deflecting dipolar iron can be controlled by controlling the direction of the current flowing through each quadrupole iron in the transmission module 201, the deflecting dipolar iron, and the quadrupole iron in the focusing module 202. This allows each of the quadrupole irons in the transmission module 201, the deflecting dipolar iron, and the quadrupole iron in the focusing module 202 to perform its respective function.

[0052] In practical applications, when the electron energy of the electron beam is fixed, the magnetic induction intensity of the quadrupole and deflector in the transmission module 201 can be fixed, and the magnitude of the magnetic induction intensity of the quadrupole in the focusing module 202 can be adjusted to allow the electron beam emitted by the beam focusing transmission system to be focused onto a target region at any depth. Alternatively, even when the electron energy of the electron beam is not fixed, the magnitude of the magnetic induction intensity of the quadrupole, deflector, and quadrupole in the transmission module 201 and the focusing module 202 can be adjusted to allow the electron beam emitted by the beam focusing transmission system to be focused onto a target region at any depth.

[0053] Specifically, the magnetic flux density of the quadrupole in the focusing module 202 can be determined based on the focusing depth corresponding to the target area, and the current flowing through the quadrupole in the focusing module 202 can be adjusted according to the magnetic flux density, so that the electron beam emitted by the focusing module 202 can be focused onto the target area. Alternatively, the magnetic flux density of the quadrupole in the transmission module 201, the deflecting diode, and the quadrupole in the focusing module 202 can be determined based on the focusing depth corresponding to the target area and the initial beam parameters of the electron beam to be focused, and the current flowing through the quadrupole in the transmission module 201, the deflecting diode, and the quadrupole in the focusing module 202 can be adjusted according to the magnetic flux density, so that the electron beam emitted by the focusing module 202 can be focused onto the target area.

[0054] The initial beam parameters can be understood as the beam parameters of the electron beam generated by an ultra-high-energy electron source (such as a laser-plasma accelerator or a high-gradient electron linear accelerator), or the beam parameters of the electron beam before it enters the beam focusing and transmission system. The initial beam parameters may include at least one of the following: electron energy, divergence angle, and beam spot size. The focusing depth can be understood as the distance between the quadrupole in the focusing module 202 and the target area, or it may be the distance between the emission port of the laser-plasma accelerator and the target area, or the distance between the surface of the target object and the target area, etc. In practical applications, the focusing depth and initial beam parameters can be input into the system as known parameters. This embodiment of the disclosure does not limit the method of obtaining the focusing depth and initial beam parameters.

[0055] It should be understood that the required magnetic flux density for the same beam parameter at different focusing depths is different, and the required magnetic flux density for different beam parameters at the same focusing depth is also different. Therefore, those skilled in the art can obtain the required magnetic flux density for each electromagnet (including the quadrupole, deflecting dipole, and quadrupole in the focusing module 202) under different beam parameters and focusing depths through theoretical analysis combined with Monte Carlo simulation verification. That is, the correspondence between different beam parameters and different focusing depths and the magnetic flux density of each electromagnet can be obtained. This correspondence can be linear or nonlinear, thereby allowing convenient control of the magnetic flux density of any electromagnet in the aforementioned beam focusing transmission system based on this correspondence. Alternatively, this correspondence can be converted into a MAP chart, and in practical applications, the required magnetic flux density of any electromagnet in the aforementioned beam focusing transmission system under any focusing depth and any initial beam parameter can be looked up using a lookup table. This disclosure does not limit the method of determining the above correspondence.

[0056] According to the embodiments of this disclosure, the electron beam is diverged in the focusing direction and focused in the parallel direction by the quadrupole in the transmission module, and the divergent electron beam emitted from the transmission module is transformed into a strongly focused beam in the focusing direction and the focused electron beam emitted from the transmission module is transformed into a parallel beam in the parallel direction by the quadrupole in the focusing module. This enables the electron beam emitted from the focusing module to be strongly focused at a large angle and flat onto the target area of ​​the target object (e.g., a lesion area inside a patient's body). Different electrons in the electron beam enter the target object at different positions and are focused on the target area within the target object. This can reduce the dose deposition of the electron beam at the entrance / exit of the target object and achieve the peak dose deposition of the electron beam in the target area. In this way, the radiation dose to other normal tissues within the target object can be greatly reduced, and the effect of electron radiotherapy can be improved. At the same time, by using deflecting dipoles, the electron beam can be deflected at a specified angle. It can also make the entire beam focusing and transmission system foldable in space, making the entire beam focusing and transmission system more compact and more suitable for miniaturized radiotherapy equipment.

[0057] As described above, the quadrupole and deflecting dipole in the transmission module 201 can use a fixed magnetic induction intensity, and by adjusting the magnetic induction intensity of the quadrupole in the focusing module 202, the electron beam emitted by the above beam focusing transmission system can be focused onto the target area at any focusing depth. Optionally, the beam focusing transmission system also includes a control module 203, which can be electrically connected to the quadrupole 2021 in the focusing module 202.

[0058] The control module 203 is used to control the quadrupole 2021 in the focusing module 202 to generate a magnetic induction intensity that matches the target area according to the focusing depth corresponding to the target area, so that the electron beam emitted by the focusing module 202 is focused on the target area.

[0059] It should be understood that magnetic fields of different magnetic induction intensities have different effects on electron beams of different energies. Therefore, the beam focusing and transmission system of the quadrupole 2021 in the focusing module 202, which is electrically connected to the control module 203, can be applied to focusing and transmission scenarios where the initial beam parameters of the electron beam are fixed. In this way, the quadrupole and the deflecting diode in the transmission module 201 have the same effect on electron beams with the same initial beam parameters. Therefore, the electron beam can be focused to the target area at any focusing depth simply by adjusting the magnetic induction intensity of the quadrupole in the focusing module 202.

[0060] Since the control module 203 is electrically connected to the quadrupole magnet 2021 in the focusing module 202, the control module 203 can supply power to the quadrupole magnet 2021 in the focusing module 202. Specifically, the control module 203 can control the magnitude of the current flowing through the quadrupole magnet 2021 in the focusing module 202 to control the magnetic induction intensity generated by the quadrupole magnet 2021 to match the target area. It should be understood that this embodiment does not limit the hardware structure or hardware type of the control module 203, as long as it can achieve its intended functions.

[0061] As described above, the focusing depth can be understood as the distance between the quadrupole in the focusing module 202 and the target area, or it can be the distance between the emission port of the ultra-high energy electron source (such as a laser plasma accelerator or a high gradient electron linear accelerator) and the target area, or it can be the distance between the surface of the target object and the target area, etc. This embodiment of the present disclosure does not limit this. In practical applications, the focusing depth can be input into the system as a known parameter. This embodiment of the present disclosure does not limit the method of obtaining the focusing depth. For example, the control module 203 can communicate with an external computing device to obtain the focusing depth of the target area; of course, the control module 203 can also directly obtain the focusing depth manually input by the user, and this embodiment of the present disclosure does not limit this.

[0062] Based on this, the control module 203 controls the quadrupole 2021 in the focusing module 202 to generate a magnetic induction intensity matching the target target area according to the focusing depth corresponding to the target area, so that the electron beam emitted by the focusing module 202 is focused and transmitted to the target target area. This includes: determining the target magnetic induction intensity that the quadrupole 2021 should have based on the focusing depth corresponding to the target target area and the pre-set correspondence between different focusing depths and the magnetic induction intensity of the quadrupole 2021; and controlling the magnitude of the current flowing through the quadrupole 2021 according to the target magnetic induction intensity that the quadrupole 2021 should have, so that the electron beam emitted by the focusing module 202 is focused on the target target area. In this way, the peak dose of the electron beam at any focusing depth in the target target area can be achieved with a fixed initial beam parameters.

[0063] As mentioned above, the required magnetic flux density varies at different focusing depths. To focus the electron beam onto the target region at any focusing depth, theoretical analysis combined with Monte Carlo simulations can be used to obtain the required magnetic flux density of the quadrupole 2021 in the focusing module 202 at different focusing depths. This establishes the correspondence between different focusing depths and the magnetic flux density of the quadrupole 2021. Based on this correspondence, the target magnetic flux density that the quadrupole 2021 should possess at any focusing depth can be quickly determined, i.e., the magnetic flux density matching the target region can be determined. This embodiment does not limit the method for determining the above correspondence.

[0064] According to embodiments of this disclosure, the control module 203 can efficiently control the quadrupole iron in the focusing module 202 of the system to generate a magnetic induction intensity that matches the target area, thereby enabling the system to efficiently focus and transmit the electron beam to the target area at any focusing depth, and achieve the peak dose deposition of the electron beam at any focusing depth.

[0065] Considering that in practice there may be a need to focus and transmit electron beams with different initial beam parameters to the target area, that is, the initial beam parameters of the electron beams entering the beam focusing and transmission system may be different, therefore, the quadrupoles 2011 and 2013 in the transmission module 201, the deflecting diode 2012, and the quadrupole 2021 in the focusing module 202 can all be electromagnets with adjustable magnetic induction intensity. This allows for the focusing and transmission of electron beams with different initial beam parameters to the target area at any focusing depth by adjusting the magnetic induction intensity of each electromagnet. Optionally, such as... Figure 5 As shown, the control module 203 can be electrically connected to the quadrupole 2011 and 2013 in the transmission module 201, the deflection diode 2012, and the quadrupole 2021 in the focusing module 202, respectively.

[0066] The control module 203 is used to control the quadrupoles 2011 and 2013 in the transmission module 201, the deflecting dipole 2012, and the quadrupole 2021 in the focusing module 202 to generate magnetic induction intensities that match the target area, based on the focusing depth corresponding to the target area and the initial beam parameters of the electron beam to be focused, so that the electron beam emitted by the focusing module 202 is focused on the target area; wherein, the initial beam parameters include at least one of the following: electron energy, divergence angle, and beam spot size.

[0067] Specifically, by controlling the deflection diode to generate a magnetic induction intensity that matches the target area, it is possible to select electrons of different energies in the incoming electron beam; by controlling the quadrupole in the transmission module and the quadrupole in the focusing module to generate magnetic induction intensities that match the target area, it is possible to control the incident position and incident angle of different electrons in the electron beam emitted by the focusing module when they enter the target object, as well as the focusing depth after entering the target object.

[0068] It should be understood that electrons in the same electron beam usually have different energies. Electrons with different energies will produce different deflection radii under the same magnetic induction intensity. Therefore, by using a deflecting dipole with a magnetic induction intensity that matches the target area, it is possible to select the energy of electrons with different energies in the incoming electron beam, so that the electrons in the electron beam entering the focusing module 202 are high-energy electrons that meet the needs of radiotherapy.

[0069] In practical applications, theoretical analysis combined with simulation experiments can be used to determine the correspondence between the magnetic induction intensity of each quadrupole in the transmission module and the focusing module under different initial beam parameters and the incident position, incident angle, and focusing depth. Based on this correspondence, according to the focusing depth corresponding to the target area and the initial beam parameters of the electron beam to be focused, the quadrupoles in the transmission module and the focusing module can be controlled to generate magnetic induction intensities that match the target area. This allows control over the incident position and incident angle of different electrons in the electron beam emitted from the focusing module when they enter the target object, as well as the focusing depth after entering the target object.

[0070] Since the control module 203 is electrically connected to the quadrupoles 2011 and 2013, the deflecting diode 2012, and the quadrupole 2021 in the focusing module 202 of the transmission module 201, the control module 203 can supply power to the quadrupoles 2011 and 2013, the deflecting diode 2012, and the quadrupole 2021 in the focusing module 202, respectively. Specifically, the control module 203 can control the magnitude of the current flowing through the quadrupoles 2011 and 2013, the deflecting diode 2012, and the quadrupole 2021 in the focusing module 202 to generate magnetic induction intensities that match the target area.

[0071] In practical applications, the control module 203 can communicate with an external computing device to obtain the focusing depth of the target area and the initial beam parameters of the electron beam; of course, the control module 203 can also directly obtain the focusing depth and initial beam parameters manually input by the user, which is not limited in this embodiment.

[0072] Based on this, the control module 203 controls the quadrupoles 2011 and 2013 in the transmission module 201, the deflecting diode 2012, and the quadrupole 2021 in the focusing module 202 to generate magnetic induction intensities matching the target area, according to the focusing depth corresponding to the target area and the initial beam parameters of the electron beam to be focused, so that the electron beam emitted by the focusing module 202 is focused on the target area. This can include: determining the target magnetic induction intensity that each of the above electromagnets should have according to the focusing depth corresponding to the target area, the initial beam parameters of the electron beam, and the pre-set different beam parameters and the correspondence between different focusing depths and the magnetic induction intensities of each electromagnet (including the quadrupole in the transmission module 201, the deflecting diode, and the quadrupole in the focusing module 202); and controlling the current flowing through each of the above electromagnets according to the target magnetic induction intensity that each of the above electromagnets should have, so that the electron beam emitted by the focusing module 202 is focused on the target area. This method enables peak dose deposition of the electron beam at any focusing depth in the target area, even when the initial beam parameters of the electron beam are not fixed.

[0073] As mentioned above, the required magnetic flux density varies with different initial beam parameters and focusing depths. To focus electron beams with different initial beam parameters onto a target region at any focusing depth, theoretical analysis combined with Monte Carlo simulations can be used to obtain the correspondence between different beam parameters, different focusing depths, and the magnetic flux density of each electromagnet. Based on this correspondence, the target magnetic flux density that each electromagnet should possess at any focusing depth and with any initial beam parameters can be quickly determined, i.e., the magnetic flux density matching each electromagnet with the target region can be determined. This disclosure does not limit the method of determining the above correspondence.

[0074] According to the embodiments of this disclosure, the control module 203 can efficiently control the quadrupole iron in the transmission module 201, the deflection diode iron, and the quadrupole iron in the focusing module 202 to generate magnetic induction intensity matching the target area, thereby enabling the system to efficiently focus and transmit an electron beam with arbitrary initial beam parameters to the target area at any focusing depth, and realize the dose deposition peak of the electron beam with arbitrary initial beam parameters at any focusing depth.

[0075] Experimental results obtained by injecting a 200 MeV electron beam (e.g., a monoenergetic electron beam with a beam size of 100 micrometers and a divergence angle of 4 mrad) generated by an ultra-high energy electron source (such as a laser plasma accelerator or a high gradient electron linear accelerator) into a body of water are presented, and the beneficial effects obtained by using the electron beam focusing system of the above-described embodiments of the present disclosure are described.

[0076] Figure 6a , Figure 6b and Figure 6c This diagram illustrates the dose distribution of an electron beam deposited in water using the beam focusing and transmission system according to an embodiment of the present disclosure. Specifically, Figure 6a This illustrates the two-dimensional slice dose distribution along the focused emission direction on the scanning plane (the plane containing the x and y axes in the figure). Figure 6b This demonstrates the two-dimensional slice dose distribution along the scanning plane in the parallel emission direction. Figure 6c The axial slice dose distribution along the x-axis and the transverse slice integral dose distribution along the x-axis are shown, such as... Figure 6a , Figure 6b and Figure 6c As shown, the dose deposited by the electron beam reaches its peak at a depth of approximately 10 cm in the water, and the inlet / outlet dose ratio along the axis is lower than the peak dose. That is, the beam focusing transmission system of this embodiment achieves flat focusing of the electron beam at a certain depth within the water body, wherein the design of each quadrupole and deflecting diode in the system conforms to the engineeringly achievable parameter range.

[0077] According to the above-described embodiment of the beam focusing transmission system, the beam focusing transmission system can utilize the opposite focusing and defocusing properties of quadrupoles in two directions to achieve a flat focusing beam focusing transmission system. The array of multiple quadrupoles achieves a large-angle flat strong focusing on the lesion area inside the human body, achieving the purpose of radiation dose deposition at a deeper focusing depth. Furthermore, by deflecting the dipoles, the ultra-high energy electron beam is deflected by 90 degrees in the near-parallel emission direction, thereby reducing the spatial scale of the beam focusing transmission system and greatly improving the compatibility of the ultra-high energy electron radiotherapy system.

[0078] According to the beam focusing transmission system of this disclosure, the conversion of ultra-high energy electron beam from pencil beam to flat, highly focused ultra-high energy electron beam can be realized, thereby achieving the deposition of peak dose in the target area of ​​the human body. Furthermore, the focusing position of the electron beam can be adjusted by adjusting the magnetic induction intensity of the quadrupole in the focusing module (while maintaining the electron beam in the parallel emission direction as approximately parallel emission), thereby adjusting the position of dose deposition to obtain better radiotherapy effect. In addition, by utilizing the property of deflecting dipoles to deflect charged beams, the beam focusing transmission system for transmitting ultra-high energy electron beams can be folded, greatly reducing the spatial scale of the entire beam focusing transmission system and the radiotherapy equipment using the beam focusing transmission system, thus adapting to miniaturized radiotherapy equipment.

[0079] Based on the beam focusing and transmission system in the above embodiments of this disclosure, this disclosure also provides a radiotherapy device, which includes: an ultra-high energy electron source for generating an electron beam; and the beam focusing and transmission system described in the above embodiments of this disclosure. The ultra-high energy electron source may include an accelerator such as a plasma accelerator or a high-gradient electron linear accelerator, and this disclosure does not limit this type of accelerator.

[0080] In one possible implementation, the aforementioned beam focusing and transmission system can be housed within the robotic arm of a radiotherapy device, and the robotic arm can rotate around the target object. The length of the robotic arm depends on the overall structure of the beam focusing and transmission system; for example, if a specific design is used... Figure 3 The beam focusing transmission system shown can shorten the length of the robotic arm to 1.2m. This allows for radiotherapy of lesions at any location and depth within the target object, increasing the range of affine therapy while significantly reducing the length of the robotic arm, thus making the radiotherapy equipment more miniaturized.

[0081] It should be understood that the target object can lie on a treatment bed, and the robotic arm can rotate around the treatment bed, thereby rotating around the target object to perform radiotherapy on any lesion area within the target object. The beam focusing transmission system of this disclosure can be applied to various radiotherapy devices, especially radiotherapy devices using ultra-high energy electron beams. This disclosure does not limit the hardware structure, device type, etc. of the radiotherapy device.

[0082] According to the embodiments of the present disclosure, the radiotherapy device can utilize the above-mentioned beam focusing and transmission system to achieve a dose peak in the lesion area with an ultra-high energy electron beam, greatly reducing the radiation dose of the electron beam to other normal tissues in the target object, improving the effect of electron radiotherapy, reducing the time consumed by electron radiotherapy, and at the same time reducing the spatial scale of the radiotherapy device, making the radiotherapy device more compact and miniaturized, and improving the application prospects of the radiotherapy device.

[0083] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A beam focusing and transmission system for ultra-high energy electron beams, characterized in that, include: The system includes a transmission module and a focusing module, wherein the electron beam to be focused enters the transmission module and the focusing module sequentially; The transmission module includes at least one quadrupole and a deflecting dipole; each quadrupole in the transmission module is used to diverge the incoming electron beam in the focusing emission direction and focus the incoming electron beam in the parallel emission direction, so that the electron beam emitted by the transmission module is an electron beam that diverges in the focusing emission direction and is focused in the parallel emission direction; wherein, the focusing emission direction is parallel to the magnetic field direction of the deflecting dipole, and the parallel emission direction is perpendicular to the magnetic field direction of the deflecting dipole. The deflecting diode in the transmission module is used to deflect the incoming electron beam by a specified angle in the parallel emission direction, so as to change the transmission direction of the incoming electron beam. The transmission direction of the electron beam emitted by the transmission module is different from the transmission direction of the electron beam before entering the transmission module. The focusing module includes a quadrupole, which is used to focus the electron beam emitted by the transmission module in the focusing emission direction and to diverge the electron beam emitted by the transmission module in the parallel emission direction, so that the electron beam emitted by the focusing module is an electron beam that is focused and emitted in the focusing emission direction and nearly parallel in the parallel emission direction. Different electrons in the electron beam emitted by the focusing module are used to enter the target object at different positions and focus on the target area within the target object. Specifically, the electron beam is diverged in the focusing direction and focused in the parallel direction by the quadrupole in the transmission module, and the divergent electron beam emitted by the transmission module is strongly focused in the focusing direction by the quadrupole in the focusing module, and the focused electron beam emitted by the transmission module is nearly parallel in the parallel direction, so that the electron beam emitted by the focusing module is strongly focused on the target area of ​​the target object at a large angle and in a flat manner.

2. The system according to claim 1, characterized in that, The system also includes a control module, which is electrically connected to the four-pole iron in the transmission module, the deflection diode iron, and the four-pole iron in the focusing module. The control module is used to control the quadrupole in the transmission module, the deflecting diode, and the quadrupole in the focusing module to generate magnetic induction intensities matching the target area, based on the focusing depth corresponding to the target area and the initial beam parameters of the electron beam to be focused, so that the electron beam emitted by the focusing module is focused on the target area; wherein, the initial beam parameters include at least one of the following: electron energy, divergence angle, and beam spot size.

3. The system according to claim 2, characterized in that, By controlling the deflection diode to generate a magnetic induction intensity that matches the target area, the energy of electrons with different energies in the incoming electron beam can be selected. By controlling the quadrupole iron in the transmission module and the quadrupole iron in the focusing module to generate magnetic induction intensity matching the target area, the incident position and incident angle of different electrons in the electron beam emitted by the focusing module when they enter the target object, as well as the focusing depth after entering the target object, can be controlled.

4. The system according to any one of claims 1 to 3, characterized in that, The specified angle includes any angle between 30 degrees and 150 degrees.

5. The system according to any one of claims 1 to 3, characterized in that, When the transmission module includes at least two quadrupoles, the deflection diode in the transmission module is located between any pair of adjacent quadrupoles in the transmission module, or before or after at least two quadrupoles in the transmission module.

6. The system according to any one of claims 1 to 3, characterized in that, The transmission module and the focusing module are disposed outside the beam transmission channel of the electron beam, wherein the beam transmission channel has a rotation angle at the deflection diode that is the same as the specified angle.

7. The system according to any one of claims 1 to 3, characterized in that, The electron beam includes an ultra-high energy electron beam with a voltage of 50 MeV to 250 MeV generated by an ultra-high energy electron source.

8. A radiotherapy device, characterized in that, include: Ultra-high energy electron source, used to generate electron beams; And, the beam focusing and transmission system as described in any one of claims 1 to 7.

9. The device according to claim 8, characterized in that, The beam focusing and transmission system is located in the robotic arm of the radiotherapy device, and the robotic arm can rotate around the target object.

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