Radiation therapy device and magnetic resonance guided radiation therapy system

Abstract

A radiotherapy device (100, 320) and a magnetic resonance guided radiotherapy system (300, 400, 500, 600, 700). The radiotherapy device (100, 320) can include an electron gun (110) and a curved beam current deflection unit (120, 409, 509, 609, 709). The beam current deflection unit (120, 409, 509, 609, 709) is configured to accelerate an electron beam output by the electron gun (110) over a range of magnetic field strengths (B0). The magnetic resonance guided radiotherapy system (300, 400, 500, 600, 700) can include the radiotherapy device (100, 320) and a magnetic resonance imaging device (310).

Description

Technical Field

[0001] This manual relates to medical devices, and more particularly to radiotherapy equipment and magnetic resonance-guided radiotherapy systems. Background Technology

[0002] Currently, radiotherapy for tumors is hampered by the difficulty in tracking tumor changes (e.g., metastasis) across different treatment courses. Today, various imaging techniques can be used to provide images of the tumor before or within each treatment course. For example, magnetic resonance imaging (MRI) equipment can be used in combination with radiotherapy equipment to provide MRI images of the tumor. Treatment systems combining MRI and radiotherapy equipment can overcome the difficulty of arranging the components of the MRI equipment (e.g., at least two main magnetic field coils, at least two shielding coils) and the components of the radiotherapy equipment (e.g., an electron accelerator) in a relatively compact space without causing interference. Therefore, there is a desire to provide a treatment system with high treatment quality and a compact structure.

[0003] Furthermore, electron accelerators can affect the performance of radiotherapy equipment. The electromagnetic fields of MRI equipment can affect, for example, the operation of one or more components of an electron accelerator (e.g., the accelerator tube). Therefore, it is desirable to provide an electron accelerator that can operate normally in a magnetic field. Summary of the Invention

[0004] According to one aspect of this specification, a radiotherapy device is provided, comprising: an electron gun and a curved beam deflection unit. The beam deflection unit is used to accelerate the electron beam output from the electron gun within a certain magnetic field strength range.

[0005] In some embodiments, the curvature of the beam deflection unit is not exactly the same at different locations.

[0006] In some embodiments, the curvature of the beam deflection unit near the electron gun is greater than the curvature of the beam deflection unit away from the electron gun.

[0007] In some embodiments, the beam deflection unit includes at least two acceleration cavities arranged in series, the curvature of the at least two acceleration cavities decreasing sequentially outward from the position closest to the electron gun.

[0008] In some embodiments, the deflection angle of the electron beam as it passes through one of the at least two accelerating cavities ranges from 0° to 15°.

[0009] In some embodiments, the at least two acceleration cavities include a first acceleration cavity, a second acceleration cavity, a third acceleration cavity, and a fourth acceleration cavity arranged sequentially outward from the position near the electron gun.

[0010] In some embodiments, the first deflection angle of the electron beam passing through the first accelerating cavity ranges from 0° to 10°; the second deflection angle of the electron beam passing through the second accelerating cavity ranges from 0° to 15°; the third deflection angle of the electron beam passing through the third accelerating cavity ranges from 0° to 5°; and the fourth deflection angle of the electron beam passing through the fourth accelerating cavity ranges from 0° to 5°.

[0011] In some embodiments, the length of the beam deflection unit ranges from 200 mm to 400 mm.

[0012] In some embodiments, the deflection angle of the electron beam passing through the beam deflection unit ranges from 0° to 30°.

[0013] In some embodiments, the magnetic field strength ranges from 0 Gs to 50 Gs.

[0014] In some embodiments, the electron gun is a radio frequency electron gun.

[0015] In some embodiments, the radio frequency electron gun includes a hot cathode disposed within the beam deflection unit.

[0016] In some embodiments, the hot cathode is disposed at one end of the beam deflection unit near the electron gun.

[0017] According to another aspect of this specification, a magnetic resonance-guided radiotherapy system is provided, comprising a radiotherapy device and an MRI device. The radiotherapy device includes an electron gun and a curved beam deflection unit. The beam deflection unit is used to accelerate the electron beam output from the electron gun within a certain magnetic field strength range. The MRI device includes a main magnet comprising at least two main magnetic field coils arranged coaxially along an axis. The MRI device may include at least two shielding coils, comprising a first shielding coil, a second shielding coil, and a shielding coil group arranged coaxially along the axis, wherein the shielding coil group is located between the first shielding coil and the second shielding coil.

[0018] In some embodiments, the shielded coil group includes a first coil group and a second coil group arranged coaxially along the axis. The first coil group or the second coil group includes a first coil and a second coil.

[0019] In some embodiments, the direction of the current in the first coil is opposite to the direction of the current in the second coil. The radius of the first coil or the second coil is larger than the radius of the at least two main magnetic field coils. The radius of the first coil is larger than the radius of the second coil.

[0020] According to another aspect of this specification, a magnetic resonance-guided radiotherapy system is provided, the system comprising a radiotherapy apparatus and an MRI apparatus. The MRI apparatus includes at least two main magnetic coils. The MRI apparatus may also include at least two magnetic shielding coils. The MRI apparatus may further include a ring cryostat, wherein the at least two main magnetic coils and the at least two magnetic shielding coils are arranged coaxially along an axis of the ring cryostat, the at least two magnetic shielding coils being disposed at a radius greater than that of the at least two main magnetic coils from the axis, the ring cryostat including at least one outer wall and at least one inner wall coaxial with the axis, the ring cryostat further including an annular groove between the at least one outer wall and the at least one inner wall, the annular groove having an opening formed on the at least one outer wall. The radiotherapy apparatus includes an electron gun and a curved beam deflection unit for accelerating an electron beam emitted by the electron gun within a range of magnetic field strength; the beam deflection unit is at least partially located within the annular groove of the ring cryostat. The radiotherapy apparatus may include a first shielding structure configured to provide magnetic shielding for at least one of the electron gun and the beam deflection unit. The radiotherapy device may include at least one second shielding structure that is substantially the same as the first shielding structure, wherein the first shielding structure and the at least one second shielding structure are respectively located at selected circumferential positions within the annular groove.

[0021] In some embodiments, the at least one second shielding structure is located at a circumferential position relative to the axis of the first magnetic shielding structure.

[0022] In some embodiments, the electron gun and the curved beam deflection unit are at least partially surrounded by the first shielding structure.

[0023] In some embodiments, the at least one second shielding structure includes more than two second shielding structures, and the first shielding structure and the at least one second shielding structure are evenly distributed within the annular groove. Attached Figure Description

[0024] This specification will be further described through exemplary embodiments. These exemplary embodiments will be described in detail with reference to the accompanying drawings. These embodiments are non-limiting exemplary embodiments, and similar reference numerals denote the same structural components or operations. These embodiments are non-limiting exemplary embodiments, and in these embodiments, the same numbers in the figures denote similar structures, wherein:

[0025] Figure 1 This is a schematic diagram of the structure of a radiotherapy device 100 according to some embodiments of this specification;

[0026] Figure 2AThis is a schematic diagram of an exemplary radiotherapy device 100 having an edge-coupled cavity, according to some embodiments of this specification;

[0027] Figure 2B This is a schematic diagram of an exemplary radiotherapy device 100 having an edge coupling cavity and an acceleration unit, according to some embodiments of this specification;

[0028] Figure 3A This is an exemplary radiotherapy system 300 shown according to some embodiments of this specification;

[0029] Figure 3B This is another exemplary radiotherapy system 300 shown according to some embodiments of this specification;

[0030] Figure 4 This is the upper part of a cross-sectional view of an exemplary radiotherapy system 400 viewed along the Z direction, according to some embodiments of this specification;

[0031] Figure 5 This is the upper part of a cross-sectional view of another exemplary treatment system 500 viewed along the Z direction, as shown in some embodiments of this specification;

[0032] Figure 6 This is a perspective view of an exemplary treatment system 600 according to some embodiments of this specification;

[0033] Figure 7 This is a cross-sectional view of the treatment system 700 as viewed along the axial direction (i.e., the Z direction) of the cryostat, according to some embodiments of this specification. Detailed Implementation

[0034] The following description is provided to enable those skilled in the art to implement and utilize this specification, and is given in a specific application scenario and its requirements. It will be apparent to those skilled in the art that various modifications can be made to the disclosed embodiments, and the general principles defined herein can be applied to other embodiments and application scenarios without departing from the principles and scope of this specification. Therefore, this specification is not limited to the described embodiments, but should be given the broadest scope consistent with the claims.

[0035] The terminology used in this specification is for describing specific exemplary embodiments only and does not limit the scope of this specification. As shown in this specification and claims, unless the context clearly indicates otherwise, words such as "a," "an," "an," and / or "the" do not specifically refer to the singular and may also include the plural. It should also be understood that, as in this specification, the terms "comprising" and "including" only indicate the presence of the stated features, integrals, steps, operations, components, and / or parts, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, components, parts, and / or combinations thereof.

[0036] These and other features, characteristics, functions and methods of operation of related structural elements, as well as the economic efficiency of component assembly and manufacture, will become more apparent from the following description of the accompanying drawings, which form part of this specification. However, it should be understood that the drawings are for illustrative and descriptive purposes only and are not intended to limit the scope of this specification. It should also be understood that the drawings are not drawn to scale.

[0037] Figure 1 This is a schematic diagram of the structure of a radiotherapy device 100 according to some embodiments of this specification. For example... Figure 1 As shown, the radiotherapy device 100 may include an electron gun 110 and a curved beam deflection unit 120. One end of the beam deflection unit 120 is connected to the electron gun 110 to accelerate the electron beam output by the electron gun 110. In some embodiments, the beam deflection unit 120 may be located within a magnetic field B0. In some embodiments, the direction of the magnetic field B0 may be perpendicular (or substantially perpendicular) to the plane containing the centerline of the curved beam deflection unit 120. In some embodiments, under the action of the magnetic field B0, the electron beam is accelerated and deflected in the beam deflection unit 120. The accelerated electron beam can then be used for target ( Figure 1 (Not shown in the image) to generate radiation rays that can be used for radiotherapy. The target can be made of materials such as aluminum, copper, stainless steel, titanium, nickel, or any combination thereof.

[0038] The beam deflection unit 120 accelerates the electron beam, causing the electron beam to have different velocities at different points within the unit. Under the influence of the magnetic field B0, the greater the velocity of the electron beam at a certain point in the beam deflection unit 120, the larger the radius of curvature of the electron beam's trajectory at that point; conversely, the smaller the radius of curvature of the electron beam's trajectory at that point. In some embodiments, a predetermined trajectory for the electron beam to move within the beam deflection unit 120 under a given magnetic field B0 can be calculated or simulated beforehand. To ensure that the electron beam travels along the predetermined trajectory within the beam deflection unit 120, thereby reducing energy loss due to collisions with the inner wall of the unit, an accelerating tube with varying curvatures can be designed according to the predetermined trajectory of the electron beam to meet the above requirements. For example, the centerline of the beam deflection unit 120 can be designed to be parallel to or coincide with the predetermined trajectory of the electron beam. For example, the beam deflection unit 120 can be used to cover the predetermined trajectory of the electron beam motion within the space of the accelerating cavity for the electron beam motion.

[0039] In some embodiments, the curvature of the beam deflection unit 120 near the electron gun 110 can be greater than the curvature of the beam deflection unit 120 away from the electron gun 110. The electron beam is accelerated in the beam deflection unit 120, and the velocity of the electron beam at the end of the beam deflection unit 120 near the electron gun 110 is less than its velocity at the end of the beam deflection unit 120 away from the electron gun 110. Therefore, the radius of curvature of the electron beam's trajectory at the end of the beam deflection unit 120 near the electron gun 110 is smaller than its radius of curvature at the other end of the beam deflection unit 120 away from the electron gun 110. Because the curvature of the beam deflection unit 120 near the electron gun 110 is greater than the curvature of the beam deflection unit 120 away from the electron gun 110, the trajectory of the beam deflection unit 120 can be matched with the trajectory of the electron beam.

[0040] In some embodiments, the beam deflection unit 120 may include one or more accelerating cavities connected end-to-end. An accelerating electric field may exist in each of the one or more accelerating cavities, allowing the electron beam to be accelerated therein. The velocity of the electron beam in the one or more accelerating cavities increases sequentially outward from the end near the electron gun 110 (e.g., along the direction of electron beam movement). In some embodiments, the curvature of one or more accelerating cavities may be designed according to the trajectory of the electron beam. For example, the curvature of one or more accelerating cavities may be designed to decrease sequentially outward from the end near the electron gun. The electric field strength in each accelerating cavity may be the same or different, and the electron beam may be accelerated at the same or different accelerations in each accelerating cavity. In some embodiments, the curvature of each accelerating cavity may be the same at all points, making the accelerating cavities easy to manufacture, and the space within the accelerating cavity for electron beam movement may be close to and / or cover the trajectory of the electron beam. In some embodiments, the curvature of each accelerating cavity may be different at all points. For example, the curvature at all points of the accelerating cavity may be the same as or similar to the trajectory of the electron beam therein. In some embodiments, the deflection angle of the electron beam through one or more accelerating cavities can range from 0° to 15° (e.g., 1°, 3°, 5°, 10°, etc.). The deflection angle of the electron beam through the accelerating cavity can be understood as the angle between the direction in which the electron beam is incident on the accelerating cavity and the direction in which it exits from the accelerating cavity. In some embodiments, the different accelerating cavities of the beam deflection unit 120 can be of the same or different types. Exemplary types of accelerating cavities may include an anode cavity, a beam focusing cavity, a coupled waveguide cavity, or a high-speed optical cavity.

[0041] By way of example only, one or more accelerating cavities may include a first accelerating cavity 121, a second accelerating cavity 122, a third accelerating cavity 123, and a fourth accelerating cavity 124, arranged sequentially from the end closest to the electron gun 110 outwards. The curvature of the first accelerating cavity 121, the second accelerating cavity 122, the third accelerating cavity 123, and the fourth accelerating cavity 124 decreases sequentially from the end closest to the electron gun outwards. The first accelerating cavity 121 may be connected to the electron gun 110 and configured to receive an electron beam from the electron gun 110. The electron beam may be emitted from the fourth accelerating cavity 124 for target firing and to generate rays for radiotherapy. In some embodiments, the first accelerating cavity 121, the second accelerating cavity 122, the third accelerating cavity 123, and the fourth accelerating cavity 124 may be of the same or different types. For example, the first accelerating cavity 121 may include an anode cavity, the second accelerating cavity 122 may include a beam focusing cavity, the third accelerating cavity 123 may include a coupled waveguide cavity, or the fourth accelerating cavity 124 may include a light speed cavity.

[0042] In some embodiments, due to the effect of the magnetic field B0, the electron beam is deflected as it passes through one or more accelerating cavities. In some embodiments, the first deflection angle θ1 of the electron beam through the first accelerating cavity 121 ranges from 0 to 10°. The second deflection angle θ2 of the electron beam through the second accelerating cavity 122 ranges from 0 to 15°. The third deflection angle θ3 of the electron beam through the third accelerating cavity 123 ranges from 0 to 5°. The fourth deflection angle θ4 of the electron beam through the fourth accelerating cavity 124 ranges from 0 to 5°. The deflection angle θ0 of the electron beam through the beam deflection unit 120, which includes the first accelerating cavity 121, the second accelerating cavity 122, the third accelerating cavity 123, and the fourth accelerating cavity 124, is the sum of the first deflection angle θ1, the second deflection angle θ2, the third deflection angle θ3, and the fourth deflection angle θ4. In some embodiments, the deflection angle θ0 ranges from 0 to 30°. As an example only, the first deflection angle θ1 can be 5°, the second deflection angle θ2 can be 10°, the third deflection angle θ3 can be 2.5°, the fourth deflection angle θ4 can be 2.5°, then the deflection angle θ0 can be 20°.

[0043] In some embodiments, the length of the beam deflection unit can range from 200 mm to 400 mm. For example, the length of the beam deflection unit 120 can be 200 mm, 250 mm, 280 mm, 350 mm, 400 mm, etc. In some embodiments, the length, deflection angle θ0, and / or curvature of different parts of the beam deflection unit 120 can be set according to the strength of the magnetic field B0.

[0044] In some embodiments, the beam deflection unit 120 may include only one accelerating cavity, the curvature of which is not exactly the same at different locations, and the curvature of different locations of the accelerating cavity decreases from near the electron gun outwards, in order to match the motion trajectory of the electron beam within it. In some embodiments, the deflection angle of the electron beam through the accelerating cavity can be in the range of 0 to 30°.

[0045] In some embodiments, the beam deflection unit 120 may include at least two accelerating cavities and a side-coupled cavity. The side-coupled cavity is connected to two adjacent accelerating cavities. The side-coupled cavity can be used to control the direction of the electric field within it, thereby controlling the electron beam to accelerate, decelerate, or move at a constant speed within at least one or both accelerating cavities connected to the side-coupled cavity. Figure 2AAs shown, the beam deflection unit 120 may include a first accelerating cavity 121, a second accelerating cavity 122, a third accelerating cavity 123, and a fourth accelerating cavity 124, as well as a first side-coupled cavity 125 connected to the first accelerating cavity 121 and the second accelerating cavity 122, a second side-coupled cavity 126 connected to the second accelerating cavity 122 and the third accelerating cavity 123, and a third side-coupled cavity 127 connected to the third accelerating cavity 123 and the fourth accelerating cavity 124, respectively. In some embodiments, the beam deflection unit 120 may be a standing wave accelerator tube. Each accelerating cavity may include one or more accelerating units. Figure 2B As shown, the first acceleration cavity 121 may include one acceleration unit 121-1, the second acceleration cavity 122 may include two acceleration units 122-1 and 122-2, the third acceleration cavity 123 may include two acceleration units 123-1 and 123-2, and the fourth acceleration cavity 124 may include two acceleration units 124-1 and 124-2. When an acceleration cavity includes two or more acceleration units, a side-coupled cavity may be provided between every two adjacent acceleration units.

[0046] In some embodiments, the intensity of the magnetic field B0 can range from 0 to 50 Gs. The magnetic field B0 can be generated by an MRI device. In some embodiments, the magnetic field B0 can be a uniform magnetic field. In some embodiments, the magnetic field B0 can also be a non-uniform magnetic field or a partially non-uniform magnetic field, wherein the partially non-uniform magnetic field is uniform in a portion of the magnetic field B0, but non-uniform in other portions of the magnetic field B0.

[0047] In some embodiments, the electron gun may include a radio frequency electron gun. The radio frequency electron gun may include at least a heating element (such as a heated filament) and a hot cathode (…). Figure 2A(Not shown in the image). The heating section can heat the hot cathode to generate an electron beam. In some embodiments, the hot cathode can be partially disposed within the beam deflection unit 120. For example, the hot cathode can be disposed within the acceleration cavity (such as the first acceleration cavity 121) of the beam deflection unit 120 near the electron gun. When the hot cathode is heated to the temperature for emitting electrons by the heating section, the electrons on the surface of the hot cathode are accelerated under the action of the radio frequency electromagnetic field of the first acceleration cavity 121. In this case, problems such as the decrease in emissivity and emission density caused by injecting the electron gun into the acceleration cavity can be solved. Using a radio frequency electron gun can improve the efficiency of the radiotherapy device operating in the magnetic field B0. Due to the effect of the magnetic field B0, the electrons of the reverse-accelerated electron beam can travel in the opposite direction, rather than from the direction of emission from the electron gun, thereby avoiding the impact of the reverse-accelerated electrons on the surface of the electron gun and improving the stability of the radio frequency electron gun. In some embodiments, the electron gun 110 can also be a grid-controlled electron gun, the anode of which can be connected to or placed within the acceleration cavity of the beam deflection unit 120 near the electron gun end. In some embodiments, the electron gun 110 may also employ other electron guns (such as the Carnot electron gun, etc.), which are not limited in this specification.

[0048] The beam deflection unit 120 and / or electron gun described in the embodiments of this specification can operate under a certain magnetic field, thereby effectively reducing the magnetic field interference of the magnetic resonance imaging equipment to the radiotherapy equipment. To further reduce the magnetic field interference of the magnetic resonance imaging equipment to the radiotherapy equipment, this specification also provides an active shielding structure (e.g., such as...). Figure 4 As shown), by optimizing the magnets in a magnetic resonance imaging (MRI) device, the magnetic field generated by the MRI device at the radiotherapy device can be reduced. In some embodiments, this specification also provides a passive shielding structure (e.g., as shown). Figure 5-7 As shown, by providing a shielding structure around the radiotherapy device, the magnetic field generated by the magnetic resonance imaging device at the radiotherapy device can be weakened. In some embodiments, the radiotherapy system may include an active shielding structure, a passive shielding structure, or any combination thereof.

[0049] Figure 3A This is an exemplary radiotherapy system 300 shown according to some embodiments of this specification. For example... Figure 3A As shown, the radiotherapy system 300 may include an MRI device 310, a radiotherapy equipment 320, and a treatment table 330.

[0050] The MRI device 310 may include an aperture 301, a main magnet 302, one or more gradient coils (not shown), and one or more radio frequency (RF) coils (not shown). The MRI device 310 may be configured to acquire image data from an imaging region. For example, the image data may relate to a tumor-related treatment area. In some embodiments, depending on the type of main magnet 302, the MRI device 310 may be a permanent magnet MRI scanner, a superconducting electromagnet MRI scanner, or a resistive electromagnet MRI scanner, etc. In some embodiments, depending on the strength of the magnetic field, the MRI device 310 may be a high-field MRI scanner, a mid-field MRI scanner, or a low-field MRI scanner, etc. In some embodiments, the MRI device 310 may be a closed-aperture (cylindrical) type, an open-aperture type, etc.

[0051] The main magnet 302 can be ring-shaped and can generate a static magnetic field B1. The main magnet 302 can be of various types, including, for example, permanent magnets, superconducting electromagnets, and resistive electromagnets. Superconducting electromagnets can include alloys such as niobium, vanadium, and technetium.

[0052] One or more gradient coils can generate magnetic field gradients to the main magnetic field B1 in the X, Y, and / or Z directions (or axes). In some embodiments, one or more gradient coils may include an X-direction (or axis) coil, a Y-direction (or axis) coil, a Z-direction (or axis) coil, etc. For example, the Y-direction coil may be based on a Maxwell coil design, and the Z-direction coil and X-direction coil may be based on a Golay coil design. As used herein, the Z-direction may also be referred to as the readout (RO) direction (or frequency encoding direction), the X-direction may also be referred to as the phase encoding (PE) direction, and the Y-direction may also be referred to as the slice selection encoding direction. In this specification, the readout direction and the frequency encoding direction are used interchangeably.

[0053] By way of example only, gradient magnetic fields may include a slice selection gradient field corresponding to the Y direction, a phase encoding (PE) gradient field corresponding to the X direction, a readout (RO) gradient field corresponding to the Z direction, etc. Gradient magnetic fields in different directions can be used to encode spatial information of the MR signal. In some embodiments, gradient magnetic fields may also be used to perform at least one of the following functions: stream coding, stream compensation, stream dephase, or any combination thereof.

[0054] One or more RF coils can transmit RF pulses to and / or receive MR signals from an object being examined (e.g., a body, substance, object). As used herein, RF pulses can include excitation RF pulses and refocusing RF pulses. In some embodiments, the excitation RF pulse (e.g., a 90-degree RF pulse) may cause the magnetization vector to move away from the direction of the main magnetic field B1. In some embodiments, the refocusing pulse (e.g., a 180-degree RF pulse) may cause the dispersive spin to rotate about an axis in the transverse plane so that the magnetization vector can be rephased at a later time. In some embodiments, the RF coils can include an RF transmitting coil and an RF receiving coil. The RF transmitting coil can transmit RF pulse signals that can excite the nuclei in the object to resonate at Larmor frequencies. The RF receiving coil can receive MR signals transmitted from the object. In some embodiments, the RF transmitting coil and the RF receiving coil can be integrated into a single coil, e.g., a transmit / receive coil. The RF coils can be of various types, such as quotient (QD) quadrature coils, phase array coils, etc. In some embodiments, different RF coils 240 can be used to scan different parts of the subject, such as head coils, knee coils, cervical spine coils, thoracic spine coils, temporomandibular joint (TMJ) coils, etc. In some embodiments, RF coils can be classified into volumetric coils and local coils according to their function and / or size. For example, volumetric coils may include cage coils, transverse electromagnetic coils, surface coils, etc. As another example, local coils may include solenoid coils, saddle coils, flexible coils, etc.

[0055] The radiotherapy device 320 may include a cylinder 312 and a base 307. The cylinder 312 may be ring-shaped. The cylinder 312 may be disposed around a main magnet 302 and intersect the main magnet 302 in the central region of the main magnet 302 along the axis 311 of the aperture 301. The cylinder 312 may house and support a radiation source configured to emit a radiation beam toward the treatment area within the aperture 301. The radiation beam may be an X-ray beam, an electron beam, a proton beam source, etc. The cylinder 312, together with the radiation source mounted thereon, may rotate about the axis 311 of the aperture 301 and / or a point referred to as the isocenter. By way of example only, the cylinder 312, together with the radiation source mounted thereon, may rotate about the axis 311 by any angle, such as 90 degrees, 180 degrees, 360 degrees, 450 degrees, or 540 degrees. The cylinder 312 may be further supported by the base 307.

[0056] It should be noted that the foregoing is provided for illustrative purposes only and is not intended to limit the scope of this specification. Various changes or modifications can be made by those skilled in the art based on the teachings of this specification. For example, the radiotherapy apparatus 320 may further include a linear accelerator configured to accelerate electrons, ions, or protons, a dose detection device, a temperature control device (e.g., a cooling device), a multi-layer collimator, and any combination thereof. However, these changes and modifications will not depart from the scope of this specification.

[0057] The treatment table 330 may include a platform 308 and a base 309. In some embodiments, the platform 308 may be horizontally movable and enter an aperture 301 of the MRI device 310. In some embodiments, the platform 308 may be movable in two, three, four, five, or six dimensions. In some embodiments, the platform 308 may be moved based on changes in the tumor (e.g., positional changes) estimated from real-time MRI images obtained during treatment.

[0058] In some embodiments, the object may be placed on platform 308 and fed into MRI apparatus 310. In some embodiments, the object may be a human patient. The human patient may be supine, prone, or laterally positioned on platform 308.

[0059] During treatment, the cylinder 312 can be configured to rotate around the main magnet 302. In some embodiments, the main magnet 302 may include a groove (not shown) on its outer wall. The groove may be arranged around the entire circumference of the main magnet 302. For example, the groove may have an annular shape around the main magnet 302 to receive at least a portion of the cylinder 312. In some embodiments, the groove may be arranged around a portion of the circumference of the main magnet 302. For example, the groove may have one or more arcuate shapes around the main magnet 302.

[0060] In some embodiments, at least a portion of the radiation source is within a groove. This arrangement can reduce the distance between the radiation source and the axis 311 of the aperture 301 along the radial direction of the main magnet 302. In some embodiments, the radiation source can move along the entire rotation path within the groove. In some embodiments, the radiation source can move along the rotation path within a groove that is not a complete circle, such as a semicircle, a 3 / 4 circle, or a 4 / 5 circle. In this case, the radiation source moves clockwise first and then counterclockwise during treatment, and the worktable can also move. The radiation source can generate a radiation beam according to one or more parameters. Exemplary parameters may include parameters of the radiation beam, parameters of the radiation source, or parameters of the platform 308. For example, parameters of the radiation beam may include radiation intensity, radiation angle, radiation distance, radiation area, radiation time, intensity distribution, etc., or any combination thereof. Parameters of the radiation source may include position, rotation angle, rotation speed, rotation direction, configuration of the radiation source, etc., or any combination thereof. In some embodiments, the radiation beam generated by the radiation source may account for energy loss of the radiation beam, for example, due to the absorption of at least a portion of the radiation beam by the main magnet 302 located in the path of the radiation beam. For example, the radiation intensity of the radiation beam can be set to be greater than the radiation intensity without energy loss, and the energy loss is compensated accordingly by absorption, for example, by the main magnet 302, so that the radiation beam of a specific intensity is directed toward the treatment area (e.g., a tumor).

[0061] Figure 3B This is another exemplary radiotherapy system 300 shown according to some embodiments of this specification. (and...) Figure 3A Compared to the radiotherapy system 300 described herein, the radiotherapy system 300 can use a gantry 306 instead of a cylinder 312. The gantry 306 can be positioned on one side of the main magnet 302. The treatment head 304 can be mounted on the gantry 306 via a treatment arm 305. The treatment head 304 can accommodate a radiation source. The gantry 306 allows the treatment head 304 to rotate about an axis 311 of the bore 301.

[0062] like Figure 3B As shown, the groove 303 may be located on the outer wall of the main magnet 302 and has an annular shape. The groove 303 may accommodate at least a portion of the treatment head 304 and provide a path for rotating the treatment head 304. This arrangement can reduce the distance between the treatment head 304 and the axis 311 of the aperture 301 in the radial direction of the main magnet 302. In some embodiments, the reduction in the distance between the treatment head 304 and the axis 311 of the aperture 301 may result in an increase in the radiation dose reaching the treatment area, for example, leading to enhanced treatment effect. In some embodiments, the width of the groove 303 in the Y direction (i.e., the axial direction of the main magnet 302) may not be less than the width of the treatment head 304 in the Y direction.

[0063] The description of the radiotherapy system 300 is for illustrative purposes only and is not intended to limit the scope of this specification. Various changes and modifications can be made based on the description in this specification by those skilled in the art. For example, the assembly and / or function of the radiotherapy system 300 may be varied or altered according to a particular embodiment. In some embodiments, the main magnet 302 of the MRI device 310 may also rotate relative to the treatment head 304. For example, the radiotherapy device 320 and the MRI device 310 may rotate synchronously or asynchronously about the same axis (e.g., axis 311). However, these changes and modifications do not depart from the scope of this specification.

[0064] Figure 4 This is the upper part of a cross-sectional view of an exemplary treatment system 400 viewed along the Z-direction, according to some embodiments of this specification. The treatment system 400 may include an MRI device configured to generate MRI data and a radiotherapy device configured to apply therapeutic radiation.

[0065] like Figure 4 As shown, the MRI apparatus may include at least two main magnetic field coils 401 (e.g., a first main magnetic field coil 401-1, a second main magnetic field coil 401-2, and a third main magnetic field coil 401-3), at least two shielding coils (e.g., shielding coil 402, shielding coil 411-1, and shielding coil 411-2), and a cryostat 403. Shielding coil 402 may include a first pair of shielding coils having a first size, namely a first shielding coil 402-a and a second shielding coil 402-b. Shielding coil 411-1 may include a second pair of shielding coils having a second size. Shielding coil 411-2 may include a third pair of shielding coils having a third size. The first, second, and third sizes may be different from each other. Shielding coil 411-1 (i.e., the second pair of shielding coils) may be located close to shielding coil 402 (i.e., the first pair of shielding coils). In some embodiments, shielding coil 411-1 (also referred to as the first coil) and shielding coil 411-2 (also referred to as the second coil) may also be referred to as a shielding coil group 411.

[0066] At least two main magnetic field coils 401, shielding coil 402 and shielding coil group 411 can be housed in a cryostat 403 and remain in a superconducting state under certain conditions (e.g., when the coils are immersed in the cooling medium in the cryostat 403).

[0067] The cryostat 403 may have a shaft 405 (e.g., Figure 3AThe annular shape of the shaft 311. At least two main magnetic field coils 401 can be arranged coaxially along the shaft 405, generating a uniform magnetic field (e.g., a static magnetic field B1) in a specific region (e.g., the region within the hole 301) when the at least two main magnetic field coils 401 carry current along the first direction. In some embodiments, the first main magnetic field coil 401-1, the second main magnetic field coil 401-2, and the third main magnetic field coil 401-3 can have the same radius or different radii.

[0068] The shielding coil 402 may also be arranged coaxially along axis 405 at a radius larger than that of the at least two main magnetic field coils 401 than the radius of the first shielding coil 402-a and the second shielding coil 402-b. That is, the radius of each of the first shielding coil 402-a and the second shielding coil 402-b is larger than the radius of each of the at least two main magnetic field coils 401. The shielding coil 402 may carry current in a second direction opposite to the first direction. The shielding coil 402 (i.e., the first pair of shielding coils) helps to shield the magnetic field generated by the at least two main magnetic field coils 401 in the external region of the MRI device.

[0069] The shielded coil group 411 may also be arranged coaxially along axis 405 at a radius larger than that of the at least two main magnetic field coils 401. That is, the radius of each of the first coil 411-1 and the second coil 411-2 is larger than the radius of each of the at least two main magnetic field coils 401. The direction of the current in each first coil 411-1 may be opposite to the direction of the current in each second coil 411-2. For example, each first coil 411-1 may include a radius designated R1, and each second coil 411-2 may include a radius designated R2, where R1 is larger than R2. Each first coil 411-1 may carry a current along a first direction, and each second coil 411-2 may carry a current along a second direction. That is, the direction of the current in the first coil 411-1 (i.e., the second pair of shielded coils) can be the same as the direction of the current in at least two main magnetic field coils 401, and the direction of the current in the second coil 411-2 (i.e., the third pair of shielded coils) can be opposite to the direction of the current in at least two main magnetic field coils 401 (i.e., the direction of the current in the third pair of shielded coils is opposite to the direction of the current in the second pair of shielded coils). In some embodiments, the shielded coils in the second pair of shielded coils (i.e., the first coil 411-1) and the shielded coils in the third pair of shielded coils (i.e., the second coil 411-2) are concentric. The concentrically arranged first coil 411-1 and second coil 411-2 can also be referred to as shielded coil group 411. Figure 4 As shown, the shielded coil group 411 may include a first coil group and a second coil group.

[0070] In some embodiments, the shielding coil group 411 may be configured to shield the magnetic field generated by an MRI apparatus (e.g., a main magnetic field coil, a magnetic shielding coil, a gradient coil) from the magnetic field generated by the MRI apparatus in a toroidal region, preventing one or more components of the radiotherapy apparatus (e.g., a linear accelerator, electron beam, a multi-leaf collimator) from being affected by the magnetic field generated by the MRI apparatus in a toroidal region. The toroidal region may have a toroidal shape with a shaft 405. The toroidal region may include a virtual outer wall with radius R1 and a virtual inner wall with radius R2. That is, the depth of the toroidal region (i.e., the thickness of the toroidal region in the radial direction) is defined as the distance from the virtual outer wall to the virtual inner wall in the radial direction, and may be equal to R1 minus R2 (R1-R2). For example, the shielding coil group 411 (e.g., a second pair of shielding coils 411-1 or a third pair of shielding coils 411-2) may be configured to shield the magnetic field between the shielding coil 402 (i.e., the first pair of shielding coils) and the main magnetic field coil 401. For example, the shielded coil group 411 (e.g., the second pair of shielded coils 411-1, the third pair of shielded coils 411-2) can be configured to reduce the magnetic field in the region within the groove (e.g., groove 408) of the annular cryogenic thermostat 403.

[0071] In some embodiments, the magnitude of the current in each coil of the shielded coil group 411 can be the same; that is, each first coil 411-1 can have the same current magnitude as each second coil 411-2. Taking a first direction pointing inward perpendicular to the XY plane as an example, the second direction can be pointing outward perpendicular to the XY plane. For the annular region, the magnetic field generated by at least two main magnetic field coils 401 (also referred to as the first magnetic field) in the annular region can be along the Y direction, while the magnetic field generated by the shielded coil group 411 (also referred to as the second magnetic field) can be opposite to the Y direction. By adjusting the magnitude of the current in each coil of the shielded coil group 411 to an appropriate magnitude, the magnitude of the first magnetic field can be equal to or approximately equal to the second magnetic field. With an appropriate magnitude of current in each coil of the shielded coil group 411, the first magnetic field and the second magnetic field can cancel each other out, so that the magnetic field in the annular region can be equal to or less than the threshold field (e.g., zero net field). The threshold field can be set by the operator or by the default setting of the radiotherapy system 400, and can be adjusted under different circumstances. For the region of the main magnetic field B1 generated by at least two main magnetic field coils 401, the magnetic field generated by the shielding coil group 411 (also called the third magnetic field) in the region of the main magnetic field B1 can be equal to or less than the threshold field, because the first coil 411-1 and the second coil 411-2 can generate two magnetic fields of approximately opposite magnitudes in the region of the main magnetic field B1, and these two magnetic fields can substantially cancel each other out. Therefore, by generating two magnetic fields of approximately opposite magnitudes through the first coil 411-1 and the second coil 411-2, the main magnetic field B1 is not affected by the shielding effect.

[0072] like Figure 4As shown, the cryostat 403 may include two chambers (e.g., simply referred to as left chamber 403-1 and right chamber 403-2). These two chambers may be located on opposite sides of the cryostat 403 in an axial direction (i.e., the direction of axis 405) and may be connected by a neck between the two chambers. The neck may have a radial dimension smaller than that of the two chambers. Each chamber has a different annular shape of its outer wall. In some embodiments, the outer wall may refer to the outermost surface of each chamber, which is annular. The two chambers and the neck may share the same inner wall, i.e., the inner wall of the cryostat 403. In some embodiments, the inner wall refers to the innermost surface of each chamber, which is also annular. In some embodiments, each chamber may accommodate at least one of at least two main magnetic field coils 401, at least one of at least two shielding coils 402, and at least one of the first coil 411-1 and the second coil 411-2 in the shielding coil group 411. For example, at least one of the at least two main magnetic field coils 401 may be arranged near the inner wall of the left chamber, such as... Figure 4 As shown, at least one of the shielding coils 402 (e.g., the first shielding coil 402-a) can be arranged near the outer wall of the left chamber 403-1, and at least one of the first coil 411-1 and the second coil 411-2 in the shielding coil group 411 (e.g., the first coil group) can be arranged near the outer wall of the left chamber 403-1 and close to the neck. Figure 4 As shown, a gap 406 can be formed between the main magnetic field coil arranged in the left chamber 403-1 and the main magnetic field coil arranged in the right chamber 403-2 to allow the radiation beam generated by the radiotherapy device to pass through. The two chambers can be fluidly connected to each other through a neck between them. The cryostat 403 may contain a cooling medium in which at least two main magnetic field coils 401 and a shielding coil 402 are immersed to achieve a superconducting state. In some embodiments, the magnetic shielding coil and the shielding coil can be replaced by permanent magnets. The direction of the magnetic field generated by the permanent magnet replacing the magnetic shielding coil may be opposite to the direction of the magnetic field of the permanent magnet replacing the shielding coil.

[0073] The cryostat 403 has a groove 408 at a radial position between the inner wall of the cryostat 403 and the outer walls of the different chambers of the cryostat 403. The groove 408 has an opening 407 formed between the outer walls of the two chambers of the cryostat 403. When viewed in perspective, the groove 408 may have an annular shape. At different radial positions, the annulus may have the same or different widths (i.e., the size in the axial direction). The groove 408 may have a depth (i.e., the thickness of the annulus in the radial direction), which is defined as the distance in the radial direction from the opening 407 to the outermost surface of the neck of the cryostat 403. Figure 4As shown, the third pair of shielding coils 411-2 can be arranged near the bottom of the groove 408, and the second pair of shielding coils 411-1 can be arranged near the opening of the groove 408.

[0074] The recess 408 can be configured to accommodate a component of a radiotherapy device. For example... Figure 4 As shown, the recess 408 can accommodate at least a portion of a radiation source, which includes an electron gun (not shown), a curved beam deflection unit 409, a collimator 412, a target 404, and a multi-leaf collimator (MLC) 410.

[0075] The curved beam deflection unit 409 can be configured to accelerate charged subatomic particles or ions to high speeds. In some embodiments, the curved beam deflection unit 409 employs microwave technology to accelerate electrons. For example, the curved beam deflection unit 409 can use high-RF electromagnetic waves to accelerate electrons in an electron beam at energy levels from 4 MeV to 22 MeV.

[0076] The curved beam deflection unit 409 can be mounted on a gantry or cylinder (e.g., gantry 306 or cylinder 312) capable of rotating around axis 405, and can emit a radiation beam from a range of circumferential positions or any circumferential position. Figure 4 As shown, the frame or cylinder can be rotated to a first position in which the curved beam deflection unit 409 is positioned above axis 405. The curved beam deflection unit 409 may include an accelerating waveguide (tube) with its axis perpendicular to axis 405. The accelerating waveguide (tube) can provide a linear path for accelerating electrons along a beam path perpendicular to axis 405. Those skilled in the art will readily understand that in other embodiments, the electrons described herein may be replaced by other particles.

[0077] Target 404 can be configured to receive accelerated charged subatomic particles or ions (e.g., an electron beam) to generate a therapeutic radiation beam. For example, the electron beam can collide with target 404 according to the bremsstrahlung effect to generate high-energy X-rays. In some embodiments, target 404 can be located near the exit window of curved beam deflection unit 409 to receive the accelerated electron beam. In some embodiments, target 404 can be made of materials such as aluminum, copper, silver, tungsten, etc., or any combination thereof. Alternatively, target 404 can be made of a combination of materials such as tungsten and copper, tungsten and silver, tungsten and aluminum, etc., or any combination thereof. Those skilled in the art will readily understand that a target is not necessary when using electron beam therapy.

[0078] The radiation beam from target 404 can pass through collimator 412 to form a beam with a specific shape (e.g., a conical beam). In some embodiments, collimator 412 may include a primary collimator, a flattening filter, and at least one secondary collimator.

[0079] The MLC 410 can be configured to reshape the radiation beam. For example, the MLC 410 can adjust the radiation shape, radiation area, etc., of the beam. The MLC 410 can be placed anywhere in the path of the radiation beam. For example, as... Figure 4 As shown, the MLC 410 can be placed near the curved beam deflection unit 409. Therefore, after being reshaped by the MLC 410, the radiation beam can further penetrate the neck of the cryostat 403 and the gap 406 between at least two main magnetic field coils to reach the treatment area. Alternatively, the MLC 410 can be placed at a relatively long distance from the linear accelerator (e.g., so that the MLC 410 can be closer to, for example, the patient to be irradiated).

[0080] MLC 410 can be fixed relative to the curved beam deflection unit 409, thereby rotating about axis 405 together with the curved beam deflection unit 409. MLC 410 may include at least two separate blades of a high atomic number material (e.g., tungsten) that can independently move into or out of the path of the radiation beam to block it. As the at least two separate blades move in and out, the shape of the radiation beam may change from the axis of the radiation beam (i.e., Figure 4 As shown by the vertical dashed line 416, different slits are formed to accommodate the cross-section of the tumor. In some embodiments, the MLC 410 may include one or more leaf layers. For example, the MLC 410 may have only one leaf layer, and the height of the MLC 410 along the axis of the radiation beam from the top to the bottom of the MLC 410 may be between 7 and 10 cm. In another example, the MLC 410 may include two layers, and the height of the MLC 410 may be at least 15 cm.

[0081] like Figure 4 As shown, the radiotherapy device can be located coaxially and / or radially between the first and second coil groups. The radiotherapy device can rotate within the annular region to minimize the influence of the magnetic field generated by the MRI device on all components of the radiotherapy device (e.g., curved beam deflection unit 409, collimator 412, target 404, MLC 410). The depth of the annular region (i.e., R1-R2) can be equal to or greater than the height of a portion of the radiotherapy device (e.g., at least a portion of the radiation source), defined as the radial distance from the top to the bottom of that portion of the radiotherapy device.

[0082] In some embodiments, the depth of the annular region may accommodate only a portion of the radiotherapy apparatus to protect that portion as much as possible from the magnetic field generated by the MRI apparatus. For example, the annular region may accommodate the target 404, collimator 412, and MLC 410. The curved beam deflection unit 409 may be outside the annular region because the accelerating waveguide (tube) of the curved beam deflection unit 409 may be surrounded by a shielding structure or the curved beam deflection unit 409 may be located relatively far from at least two main magnetic field coils 401. The shielding structure may include at least two shielding layers to shield the magnetic field generated by the MRI apparatus from the influence of the magnetic field on electrons, and / or to absorb radiation generated by the radiation beam of the curved beam deflection unit 409 from the influence of at least two main magnets 401. Again, for example, the annular region may accommodate the curved beam deflection unit 409 and the target 404. The collimator 412 and MLC 410 may be outside the annular region.

[0083] Figure 5 The upper portion of a cross-sectional view of another exemplary treatment system 500, viewed along the Z-direction, is shown according to some embodiments of this specification. The treatment system 500 may include a magnetic resonance imaging (MRI) device configured to generate MRI data and a radiotherapy device configured to apply radiotherapy.

[0084] like Figure 5 As shown, the MRI device may include at least two main magnetic coils 501, at least two magnetic shielding coils 502, and a cryostat 503.

[0085] At least two main magnetic coils 501 and at least two magnetic shielding coils 502 can be housed in a cryostat 503 and maintained in a superconducting state under certain conditions (e.g., when the two coils are immersed in the cooling medium in the cryostat 503).

[0086] The cryostat 503 may have a ring shape with a shaft 505 (e.g., Figure 3A (Axis 311 in the middle). When at least two main magnetic coils 501 transmit current along the first direction, the at least two main magnetic coils 501 can be arranged coaxially along axis 505 to generate a uniform magnetic field (e.g., main magnetic field B1) in a specific region (e.g., the region within hole 301).

[0087] At least two magnetic shielding coils 502 may also be arranged coaxially along axis 505 at a radius larger than that of the at least two main magnetic coils 501. The at least two magnetic shielding coils 502 may carry current in a second direction opposite to the first direction. The at least two magnetic shielding coils 502 can help shield the magnetic field generated by the at least two main magnetic coils 501 on an area outside the MRI device.

[0088] like Figure 5 As shown, the cryostat 503 may include two chambers (e.g., referred to as left chamber 503-1 and right chamber 503-2). The two chambers may be located on opposite sides of the cryostat 503 in an axial direction (i.e., the direction of axis 505) and may be connected by a neck between the two chambers. The radial dimension of the neck may be smaller than that of the two chambers. Each chamber may have an annulus with a different outer wall. In some embodiments, the outer wall may refer to the outermost surface of each chamber that has an annular shape. The two chambers and the neck may share the same inner wall, i.e., the inner wall of the cryostat 503. In some embodiments, the inner wall may refer to the innermost surface of each chamber, which also has an annular shape. In some embodiments, each chamber may house at least one coil of at least two main magnetic coils 501 and at least one coil of at least two magnetic shielding coils 502. For example, at least one coil of at least two main magnetic coils 501 may be arranged near the inner wall of the left chamber 503-1, and at least one coil of at least two magnetic shielding coils 502 may be arranged near the outer wall of the left chamber 503-1. A gap 506 may be formed between the main magnetic coils arranged in the left chamber 503-1 and the right chamber 503-2, allowing a radiation beam generated by the radiotherapy device to pass through. The two chambers may be in fluid communication with each other through a neck between them. The cryostat 503 may contain a cooling medium in which at least two main magnetic coils 501 and at least two magnetically shielded coils 502 are immersed to achieve a superconducting state.

[0089] The cryostat 503 may have a groove 508 at a radial position between the inner wall of the cryostat 503 and the outer walls of the different chambers of the cryostat 503. The groove 508 may have an opening 507 formed between the outer walls of the two chambers of the cryostat 503. When viewed in perspective, the groove 508 may have an annular shape. The annulus may have the same or different widths (i.e., dimensions in the axial direction) at different radial positions. The groove 508 may have a depth (i.e., the thickness of the annulus in the radial direction), which is defined as the distance in the radial direction from the opening 507 of the cryostat 503 to the outermost surface of the neck.

[0090] The recess 508 can be configured to accommodate a component of a radiotherapy device. For example... Figure 5 As shown, the groove 508 can accommodate a radiation source, which includes a curved beam deflection unit 509, a shielding structure 511, a collimator 512, a target 504, and a multi-leaf collimator (MLC) 510.

[0091] The curved beam deflection unit 509 can be configured to accelerate charged subatomic particles or ions to high speeds. In some embodiments, the curved beam deflection unit 509 can use microwave technology to accelerate electrons. For example, the curved beam deflection unit 509 can use high-RF electromagnetic waves to accelerate electrons in an electron beam with an energy range between 4 MeV and 22 MeV.

[0092] The accelerating waveguide (tube) of the curved beam deflection unit 509 can be at least partially surrounded by the shielding structure 511.

[0093] In some embodiments, the shielding structure 511 may provide a cavity coaxial with the longitudinal axis of the tube of the curved beam deflection unit 509, wherein at least one end is open to allow the radiation beam emitted from the curved beam deflection unit 509 to pass through. In some embodiments, the shielding structure 511 may have any configuration. For example, the shielding structure 511 may include an annular space on the left side of the recess (i.e., the side near the left chamber) and an annular plate on the right side of the recess (i.e., the side near the right chamber), having the plate connecting the two rings. Alternatively, the rings may be replaced by separate arc segments. It should be noted that the shielding structure 511 may be of any shape, as long as at least one end of the shielding structure 511 is open to allow the radiation beam emitted from the curved beam deflection unit 509 to pass through. Details of exemplary configurations of the shielding structure 511 can be found elsewhere in this specification (e.g., Figures 6-7 (and its description).

[0094] In some embodiments, shielding structure 511 may include at least two shielding layers. At least one of the at least two shielding layers may be used to reduce magnetic interference between one or more components of the MRI apparatus and the radiotherapy equipment. For example, shielding structure 511 may include a configured magnetic shielding layer for shielding magnetic fields generated by the MRI apparatus (e.g., main magnetic coil, magnetic shielding coil, gradient coil) from the influence of the magnetic field on electrons.

[0095] Additionally, at least one of the at least two shielding layers may be used to reduce RF and / or microwave interference between one or more components of the MRI apparatus and the radiotherapy equipment. For example, shielding structure 511 may include a configured electromagnetic shielding layer for shielding RF signals generated by the MRI apparatus (e.g., RF coils) and microwaves generated by the radiotherapy equipment.

[0096] At least two shielding layers may be made of the same and / or different materials. For example, both the electromagnetic shielding layer and the magnetic shielding layer may be made of materials with high magnetic susceptibility and permeability (e.g., non-oriented silicon steel), or one of the electromagnetic shielding layer and the magnetic shielding layer may be made of a material with high electrical conductivity and magnetic permeability. In some embodiments, the at least two shielding layers may be magnetically and / or electrically isolated from each other by a suitable dielectric material (e.g., air or plastic).

[0097] Additionally or alternatively, at least one of the at least two shielding layers may be used to protect one or more components of the MRI apparatus from radiation generated by the curved beam deflection unit 509. For example, one of the at least two shielding layers may be made of a material capable of absorbing radiation generated by the radiant beam from the curved beam deflection unit 509. Exemplary materials capable of absorbing radiation may include materials for absorbing photon rays and / or materials for absorbing neutron rays. Exemplary materials for absorbing photon rays may include steel, aluminum, lead, tungsten, etc., alloys thereof, or any combination thereof. Exemplary materials for absorbing neutron rays may include boron, graphite, etc., alloys thereof, or any combination thereof. It should be noted that in some embodiments, the shielding structure 511 may be made solely of radiation-absorbing materials, without materials with high magnetic susceptibility and permeability. In this way, the shielding structure 511 may provide radiation shielding for only one or more components of the MRI apparatus.

[0098] Target 504 can be configured to receive accelerated charged subatomic particles or ions (e.g., an electron beam) to generate a radiation beam for radiotherapy. For example, based on the bremsstrahlung effect, the electron beam can collide with target 504 to generate high-energy X-rays. In some embodiments, target 504 may be located near the exit window of curved beam deflection unit 509 to receive the accelerated electron beam. In some embodiments, target 504 may be made of a material including aluminum, copper, silver, tungsten, etc., or any combination thereof. Alternatively, target 504 may be made of composite materials, including alloys of tungsten and copper, tungsten and silver, tungsten and aluminum, etc., or any combination thereof.

[0099] The emitted beam from the target 504 can pass through the collimator 512 to form a beam with a specific shape (e.g., a conical beam). In some embodiments, the collimator 512 may include a primary collimator, a leveler, and at least one secondary collimator.

[0100] The MLC 510 can be configured to reshape the emitted beam. For example, the MLC 510 can adjust the shape of the emitted beam, the area it illuminates, etc. The MLC 510 can be placed anywhere in the path of the emitted beam. For example, the MLC 510 can be placed close to the curved beam deflection unit 509, such as... Figure 5As shown. Therefore, after being reshaped by the MLC 510, the radiation beam can further pass through the neck of the cryostat 503 and the gap 506 between at least two main magnetic coils to reach the treatment area. For example, the MLC 510 can be placed at a relatively long distance from the linear accelerator, allowing the MLC 510 to be closer, for example, to the patient to be irradiated.

[0101] MLC 510 can be fixed relative to the curved beam deflection unit 509, thereby rotating about axis 505 together with the curved beam deflection unit 509. MLC 510 may include at least two separate high-atomic-number material (e.g., tungsten) blades that independently enter and exit the path of the emitted beam to block it. As the at least two separate blades move in and out, the shape of the emitted beam can change, forming different grooves to simulate the beam's axis (i.e., Figure 5 The image shows a cross-section of the tumor as observed by the vertical dashed line 516. In some embodiments, the MLC 510 may include one or more leaf layers. For example, the MLC 510 may have only one leaf layer, and the height of the MLC 510 along the axis of the radiation beam may be between 7 and 10 cm. As another example, the MLC 510 may include two layers, and the height of the MLC 510 may be at least 15 cm.

[0102] Figure 6 A perspective view of an exemplary treatment system 600 according to some embodiments of this specification is shown.

[0103] like Figure 6 As shown, the treatment system 600 may include a hole 601, an annular cryogenic thermostat 603 with a shaft 605, a groove 608, a curved beam deflection unit 609, and a magnetic shielding device.

[0104] The magnetic shielding device may include a first shielding structure 611 and at least two second shielding structures, including second shielding structure 631a, second shielding structure 631b, etc.

[0105] In some embodiments, all shielding structures may be identical to each other. For example, the second shielding structure 631a and the second shielding structure 631b may be made of the same material and have the same structure as the first shielding structure 611.

[0106] The curved beam deflection unit 609 and the electron gun (not shown) can be surrounded or substantially surrounded by a first shielding structure 611. Specifically, the first shielding structure 611 may include a first plate located on one side of the curved beam deflection unit 609 along the circumferential direction of the groove 608 and a second plate located on the opposite side of the curved beam deflection unit 609 along the circumferential direction of the groove 608. The first and second plates may be symmetrical to each other with respect to the axis of the curved beam deflection unit 609. The first and second plates may form a surrounding structure to surround and / or retain the curved beam deflection unit 609. Each of the two plates may have a shape similar to the symbol "I", which provides a continuous path along the axial direction (i.e., the direction of axis 605) of the cryostat 603 to allow the magnetic field to pass through. Because the two plates of the first shielding structure 611 are made of at least one material with high magnetic susceptibility and / or permeability, the magnetic field can be conducted by the two plates and retained in the region formed between them, thereby achieving magnetic shielding of the curved beam deflection unit 609. In some embodiments, each of the two plates may be arranged radially about axis 605, and at least one side of each of the two plates may point towards axis 605.

[0107] In some embodiments, the first plate and the second plate may be connected to each other on both sides of the curved beam deflection unit 609 along the axial direction of the cryostat 603, thereby forming a closed loop around the curved beam deflection unit 609. In some embodiments, the first plate and the second plate may be separated from each other on both sides of the curved beam deflection unit 609 along the axial direction of the cryostat 603, thereby forming a semi-closed loop substantially around the curved beam deflection unit 609. It should be noted that the configuration of the first shielding structure 611 is not limited, and any other configuration (e.g., a hollow cylinder or other shapes with curved sides) may be used to achieve magnetic shielding.

[0108] In some embodiments, the presence of the first shielding structure 611 within the magnetic field of the MRI device may affect the magnetic field (e.g., distorting its distribution and causing magnetic field inhomogeneity). To correct the magnetic field distortion caused by the first shielding structure 611, similar magnetic shielding structures of the magnetic shielding device, including second shielding structures 631a, 631b, etc., may also be placed within the recess 608. In some embodiments, all magnetic shielding structures may be identical to each other. For example, the second shielding structures 631a and 631b may be made of the same material and have the same structure as the first shielding structure 611. The first shielding structure 611, the second shielding structure 631a, the second shielding structure 631b, etc., may be mounted on the gantry or roller (not shown) of the treatment system 600 to achieve synchronous rotation with the curved beam deflection unit 609.

[0109] In some embodiments, the first shielding structure 611, the second shielding structure 631a, the second shielding structure 631b, etc., can be positioned at selected symmetrical circumferential locations around axis 605. For example, all magnetic shielding structures can be uniformly distributed within the groove 608. Each magnetic shielding structure can correspond to an opposite or opposite counterpart. Each magnetic shielding structure and its corresponding portion can be symmetrical about axis 605. As used herein, if two magnetic shielding structures are symmetrical about axis 605, the two magnetic shielding structures can be considered opposite or opposite.

[0110] Figure 7 A cross-sectional view of the treatment system 700, viewed along the axial direction (i.e., the Z direction) of the cryostat, is shown according to some embodiments of this specification.

[0111] like Figure 7 As shown, the first shielding structure 711, the second shielding structure 721, and the second shielding structures 731a, 731b, 731c, and 731d can be evenly distributed within the groove 708 and around the axis 705 of the hole 701. The distance between any two adjacent shielding structures can be the same. The second shielding structure 721 can be the opposite or relative counterpart of the first shielding structure 711. If the second shielding structure 721 is rotated 170 degrees clockwise around the axis 705 to the position of the first shielding structure 711, then the second shielding structure 721 can be identical to the first shielding structure 711. All magnetic shielding structures can be fixed relative to the curved beam deflection unit 709, and therefore can rotate synchronously with the curved beam deflection unit 709.

[0112] The basic concepts have been described above. It is obvious that the above disclosure is merely illustrative and does not constitute a limitation of this specification for those skilled in the art who have read this application. Although not explicitly stated herein, various modifications, improvements, and corrections may be made to this specification by those skilled in the art. These changes, improvements, and modifications are intended to be proposed in this specification and are within the spirit and scope of the exemplary embodiments described herein.

[0113] Furthermore, this specification uses specific terms to describe embodiments thereof. For example, "an embodiment," "an embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of this specification. Therefore, it should be emphasized and understood that multiple references to "an embodiment," "an embodiment," or "alternative embodiment" in various parts of this specification do not necessarily refer to the same embodiment. Moreover, certain features, structures, or characteristics in one or more embodiments of this specification can be appropriately combined.

[0114] Furthermore, those skilled in the art will understand that various aspects of this specification can be described and illustrated in several patentable ways, including any new and useful combination of processes, machines, products, or substances, or any new and useful improvements thereof. Accordingly, various aspects of this specification can be implemented entirely in hardware, entirely in software (including firmware, resident software, microcode, etc.), or a combination of hardware and software. All of the above hardware or software may be referred to as a “unit,” “module,” or “system.” Furthermore, various aspects of this specification may take the form of a computer program product embodied in one or more computer-readable media having computer-readable program code.

[0115] Furthermore, unless expressly stated in the claims, the order of processing elements and sequences, the use of numbers and letters, or other names described in this specification are not intended to limit the order of the processes and methods described herein. Although various examples of inventive embodiments that are currently considered useful have been discussed in the foregoing disclosure, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments; rather, the claims are intended to cover all modifications and equivalent combinations that conform to the substance and scope of the embodiments described herein. For example, while the implementation of the various components described above can be embodied in a hardware device, it can also be implemented as a purely software solution, such as an installation on an existing server or mobile device.

[0116] Similarly, it should be noted that, in order to simplify the description disclosed in this specification and thus aid in the understanding of one or more embodiments of the invention, multiple features may sometimes be grouped into a single embodiment, drawing, or description thereof in the foregoing description of the embodiments. However, this approach in the specification should not be construed as reflecting an intention that the claimed subject matter requires more features than expressly recited in each claim. Rather, the body of the invention should possess fewer features than those in the single embodiment described above.

[0117] In some embodiments, numbers describing the quantity of components and attributes are used. It should be understood that such numbers used in the description of embodiments are modified in some examples with the terms "approximately," "approximately," or "generally." Unless otherwise stated, "approximately," "approximately," or "generally" indicates that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may be changed depending on the characteristics required by individual embodiments. In some embodiments, numerical parameters should take into account specified significant digits and employ a general method of digit reservation. Although the numerical ranges and parameters used to confirm their breadth of range in some embodiments of this specification are approximate values, in specific embodiments, such values ​​are set as precisely as feasible.

[0118] All patents, patent applications, patent application publications, and other materials (such as papers, books, specifications, publications, records, things, and / or similar items) mentioned herein are incorporated herein by reference in their entirety for all purposes, except for any prosecution documents relating to the foregoing, any foregoing documents that are inconsistent with or conflict with this document, or any foregoing documents that limit the broad scope of the claims sooner or later to this document. For example, if there is any inconsistency or conflict between the description, definitions, and / or use of terminology associated with any incorporated material and the terminology associated with this document, the terminology used in the description, definitions, and / or this document shall prevail.

[0119] Finally, it should be understood that the embodiments described in this specification are merely illustrative of the principles of the embodiments described herein. Other variations may also fall within the scope of this specification. Therefore, alternative configurations of the embodiments described herein are intended to be illustrative rather than limiting, and are considered consistent with the teachings of this specification. Accordingly, the embodiments described herein are not limited to those explicitly introduced and described herein.

Claims

1. A radiotherapy device, characterized in that, include: An electron gun and a beam deflection unit, wherein the beam deflection unit includes one or more accelerating cavities, the one or more accelerating cavities being curved for accelerating the electron beam output from the electron gun, the one or more accelerating cavities being located within a magnetic field generated by a magnetic resonance imaging device, the magnetic field causing the electron beam to deflect in the one or more accelerating cavities, and the curvature of the one or more accelerating cavities decreasing sequentially outward from the position closest to the electron gun.

2. The radiotherapy device as described in claim 1, characterized in that, The curvature of the beam deflection unit is not exactly the same at different locations.

3. The radiotherapy device as described in claim 2, characterized in that, The curvature of the beam deflection unit near the electron gun is greater than the curvature of the beam deflection unit away from the electron gun.

4. The radiotherapy device as described in claim 1, characterized in that, The deflection angle of the electron beam as it passes through one or more of the accelerating cavities ranges from 0° to 15°.

5. The radiotherapy device as described in claim 1, characterized in that, The one or more acceleration cavities include a first acceleration cavity, a second acceleration cavity, a third acceleration cavity, and a fourth acceleration cavity arranged sequentially outward from the position near the electron gun.

6. The radiotherapy device as described in claim 5, characterized in that, The first deflection angle of the electron beam passing through the first acceleration cavity ranges from 0° to 10°. The second deflection angle of the electron beam passing through the second acceleration cavity ranges from 0° to 15°. The third deflection angle of the electron beam passing through the third acceleration cavity ranges from 0° to 5°; The fourth deflection angle of the electron beam passing through the fourth acceleration cavity ranges from 0° to 5°.

7. The radiotherapy device as described in claim 1, characterized in that, The length of the beam deflection unit ranges from 200mm to 400mm.

8. The radiotherapy device as described in claim 1, characterized in that, The deflection angle of the electron beam passing through the beam deflection unit ranges from 0° to 30°.

9. The radiotherapy device as described in claim 1, characterized in that, The electron gun is a radio frequency electron gun.

10. The radiotherapy device as described in claim 9, characterized in that, The radio frequency electron gun includes a hot cathode disposed within the beam deflection unit.

11. The radiotherapy device as described in claim 10, characterized in that, The hot cathode is located at one end of the beam deflection unit near the electron gun.

12. A magnetic resonance-guided radiotherapy system, characterized in that, This includes radiotherapy equipment and magnetic resonance imaging equipment; The radiotherapy device includes an electron gun and a beam deflection unit. The beam deflection unit includes one or more acceleration cavities. The one or more acceleration cavities are curved and are used to accelerate the electron beam output by the electron gun in a magnetic field generated by the magnetic resonance imaging device. The magnetic field causes the electron beam to deflect in the one or more acceleration cavities. The curvature of the one or more acceleration cavities decreases sequentially from the position closest to the electron gun outwards. The magnetic resonance imaging device includes: The main magnet includes at least two main magnetic field coils arranged coaxially along the axis; and At least two shielding coils, including a first shielding coil, a second shielding coil, and a shielding coil group arranged coaxially along the axis, wherein the shielding coil group is located between the first shielding coil and the second shielding coil.

13. The radiotherapy system as claimed in claim 12, characterized in that, The shielding coil group includes a first coil group and a second coil group arranged coaxially along the axis. The first coil group or the second coil group includes a first coil and a second coil.

14. The radiotherapy system as claimed in claim 13, characterized in that, The direction of the current in the first coil is opposite to the direction of the current in the second coil; and / or The radius of the first coil or the second coil is greater than the radius of the at least two main magnetic field coils; and / or The radius of the first coil is greater than the radius of the second coil.

15. A magnetic resonance-guided radiotherapy system, the system comprising a radiotherapy device and a magnetic resonance imaging device, characterized in that, The magnetic resonance imaging device includes: At least two main magnetic coils; At least two magnetically shielded coils; and A ring-shaped cryogenic thermostat, wherein at least two main magnetic coils and at least two magnetic shielding coils are arranged coaxially along the axis of the ring-shaped cryogenic thermostat, the at least two magnetic shielding coils are disposed at a radius greater than that of the at least two main magnetic coils from the axis, the ring-shaped cryogenic thermostat includes at least one outer wall and at least one inner wall coaxial with the axis, the ring-shaped cryogenic thermostat further includes an annular groove between the at least one outer wall and the at least one inner wall, the annular groove having an opening formed on the at least one outer wall; The radiotherapy device includes an electron gun and a curved beam deflection unit. The beam deflection unit includes one or more accelerating cavities, which are curved to accelerate the electron beam emitted by the electron gun. The accelerating cavities are located within the magnetic field generated by the magnetic resonance imaging device, which deflects the electron beam. The curvature of the accelerating cavities decreases sequentially outwards from the position closest to the electron gun. The beam deflection unit is at least partially located within the annular groove of the annular cryostat. A first shielding structure is configured to provide magnetic shielding for at least one of the electron gun and the beam deflection unit.

16. The radiotherapy system as claimed in claim 15, characterized in that, The radiotherapy device further includes at least one second shielding structure located at a circumferential position relative to the axis of the first shielding structure.

17. The radiotherapy system according to claim 15, characterized in that, The electron gun and the curved beam deflection unit are at least partially surrounded by the first shielding structure.

18. The radiotherapy system according to claim 15, characterized in that, The radiotherapy device further includes more than two second shielding structures, and the first shielding structure and the more than two second shielding structures are evenly distributed within the annular groove.

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