CN111729212A

CN111729212A - Cathode heater of microwave source, cathode and radiotherapy equipment

Info

Publication number: CN111729212A
Application number: CN202010731106.4A
Authority: CN
Inventors: 傅费超; 邹剑雄; 王理; 倪成
Original assignee: Shanghai United Imaging Healthcare Co Ltd
Current assignee: Shanghai United Imaging Healthcare Co Ltd
Priority date: 2020-07-27
Filing date: 2020-07-27
Publication date: 2020-10-02

Abstract

The embodiment of the application discloses a cathode heater, a cathode and radiotherapy equipment of a microwave source, wherein the cathode heater comprises a spiral filament, and the filament comprises a first core body and a second core body which are adjacently arranged along the radial direction of the spiral filament; the cathode heater works in a first magnetic field, when the first core and the second core are electrified, the current directions of the first core and the second core are opposite, and the ampere force applied to the first core and the second core in the first magnetic field is opposite.

Description

Cathode heater of microwave source, cathode and radiotherapy equipment

Technical Field

The present application relates generally to radiotherapy apparatus and more particularly to a cathode heater, cathode and radiotherapy apparatus of a microwave source.

Background

Radiation therapy is widely used in cancer treatment and also to assist in assessing other health conditions. Radiotherapy is typically performed using a radiotherapy apparatus (e.g., a linear accelerator). In a radiotherapy apparatus, a microwave source consisting of an anode and a cathode is configured to generate microwave pulses (or radio frequency pulses) to control the generation of a radiation beam (e.g. X-rays). Microwave sources are an important component of radiotherapy apparatus. The microwave source generally consists of a cathode and an anode, and the cathode heater is an important component of the cathode.

Disclosure of Invention

In a first aspect, one of the embodiments of the present application provides a cathode heater of a microwave source, which includes a filament in a spiral shape, where the filament includes a first core and a second core that are adjacently disposed along a radial direction of the spiral shape; the cathode heater works in a first magnetic field, when the first core and the second core are electrified, the current directions of the first core and the second core are opposite, and the ampere force applied to the first core and the second core in the first magnetic field is opposite.

In some embodiments, the direction of the first magnetic field is parallel to the direction of the axis of the coiled filament.

In some embodiments, the first core is helically wound to form a first helical cylinder and the second core is helically wound to form a second helical cylinder, the first helical cylinder having a diameter less than a diameter of the second helical cylinder; on any cross-section perpendicular to the axis of the coiled filament, the first core is subjected to a first ampere force in the first magnetic field in a direction radially outward, and the second core is subjected to a second ampere force in the first magnetic field in a direction radially inward.

In some embodiments, the first core and the second core are filled with an insulating material therebetween.

In some embodiments, the cathode heater further comprises an insulating support layer, the filament being embedded in the insulating support layer.

In some embodiments, the first core and the second core are configured to form the same filament; alternatively, the first core and the second core are configured to form two filaments.

In some embodiments, the current values of the first core and the second core are equal.

In a second aspect, one of the embodiments of the present application provides a cathode heater of a microwave source, the cathode heater operating in a first magnetic field; the cathode heater comprises one or more lampposts, and the length direction of the one or more lampposts is parallel to the direction of the first magnetic field.

In some embodiments, the cathode heater comprises a lamp post, the lamp post being an annular lamp post; alternatively, the cathode heater includes a plurality of lamp posts arranged at a distance from each other.

In some embodiments, the cathode heater further comprises a first wiring member and a second wiring member, both ends of the lamp post are fixed to the first wiring member and the second wiring member, respectively, and both ends of the lamp post are connected to a power source through leads, respectively.

In some embodiments, the cathode heater further comprises an insulating support layer in which the lamp post is embedded.

In a third aspect, one of the embodiments of the present application provides a cathode of a microwave source, which includes a cathode heater of the microwave source according to any one of the aspects of the first aspect or the second aspect; the cathode further includes a thermionic electron emitter configured to release electrons when heated by the cathode heater.

In a fourth aspect, one of the embodiments of the present application provides a radiotherapy apparatus comprising a linear accelerator, the linear accelerator comprising: an electron generator for emitting electrons; a microwave source for generating microwaves, the microwave source comprising an anode block and a cathode, the cathode comprising a cathode heater of the microwave source of any one of the first or second aspects; an accelerating tube for accelerating electrons emitted by the electron generator in response to the microwaves.

Drawings

The present application will be further explained by way of exemplary embodiments, which will be described in detail by way of the accompanying drawings. These embodiments are not intended to be limiting, and like reference numerals refer to like elements throughout, wherein:

FIG. 1 is a schematic diagram of a filament of a cathode heater according to some embodiments of the present application;

FIG. 2 is a partial cross-sectional view of a coiled filament of a cathode heater taken along its axis in cross-section according to some embodiments of the present application;

FIG. 3 is a schematic diagram of a cathode heater of a microwave source according to further embodiments of the present application;

FIG. 4 is a schematic view of a radial cross-section of an annular lamp post of a cathode heater according to further embodiments of the present application;

FIG. 5 is a schematic view of an exemplary radiation therapy system shown in accordance with some embodiments of the present application;

FIG. 6 is a schematic diagram of exemplary components of a linear accelerator shown in accordance with some embodiments of the present application;

FIG. 7A is a cross-sectional view of an exemplary microwave source shown in accordance with some embodiments of the present application;

FIG. 7B is a different form of an anode block in a microwave source according to some embodiments of the present application;

FIG. 7C is an exemplary profile of a cathode in a microwave source according to some embodiments of the present application;

FIG. 8 is a cross-sectional view of an exemplary microwave source shown in accordance with some embodiments of the present application;

fig. 9 is a cross-sectional view of an exemplary microwave source shown in accordance with some embodiments of the present application.

Detailed Description

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings used in the description of the embodiments will be briefly introduced below. However, it will be apparent to one skilled in the art that the present application may be practiced without these specific details. In other instances, well known methods, procedures, systems, components, and/or circuits have been described in high-profile detail herein in order to avoid unnecessarily obscuring aspects of the present application. It will be apparent to those of ordinary skill in the art that various changes can be made to the disclosed embodiments and that the general principles defined in this application can be applied to other embodiments and applications without departing from the principles and scope of the application. Thus, the present application is not limited to the embodiments shown, but is to be accorded the widest scope consistent with the claims.

The terminology used in the description presented herein is for the purpose of describing particular example embodiments only and is not intended to limit the scope of the present application. As used herein, the singular forms "a", "an" and "the" may include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, components, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, and/or groups thereof.

These and other features, aspects, and advantages of the present application, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description of the accompanying drawings, all of which form a part of this specification. It is to be understood, however, that the drawings are designed solely for the purposes of illustration and description and are not intended as a definition of the limits of the application. It should be understood that the drawings are not to scale.

Unless otherwise noted, the following description is provided with respect to an exemplary embodiment of a medical device including a microwave source (e.g., a magnetron). It should be understood, however, that this is for illustrative purposes only and is not intended to limit the scope of the present application. The microwave sources disclosed herein may also be suitable for other applications (e.g., microwave ovens, particle accelerators, etc.). By way of example only, the medical device may comprise a radiation therapy device, such as an Image Guided Radiation Therapy (IGRT) device. IGRT devices may include an imaging component (e.g., an MRI device, a PET device, or a CT device) and a radiation therapy component (e.g., a linac).

In some embodiments, the microwave source may generate microwaves in one or more frequency ranges, and the microwave source may be a magnetron. The microwave source may include a cathode and an anode, and electrons discharged from the cathode may be directed to the anode and resonate in a resonant cavity of the anode, thereby causing the microwave source to emit microwaves. Wherein the cathode may include a thermionic emitter and a cathode heater, the thermionic emitter being capable of releasing electrons when the thermionic emitter is heated by the cathode heater. The microwave source may include a cathode having a cathode heater as described in embodiments herein, for example, the microwave source may include a cathode having a cathode heater including a filament in a spiral shape including a first core and a second core disposed radially adjacent to each other. When the first core and the second core are electrified, the current directions of the first core and the second core are opposite, and the ampere force applied to the first core and the second core in the magnetic field is opposite, so that the deformation of the traditional single-spiral filament caused by the radial ampere force applied to the traditional single-spiral filament in the magnetic field can be reduced. Such a cathode heater may extend the useful life of the cathode and microwave source.

Fig. 1 is a schematic diagram of a filament of a cathode heater according to some embodiments of the present application, and fig. 2 is a partial cross-sectional view of a filament of a cathode heater according to some embodiments of the present application, taken along a cross-section of the filament along an axis of the filament. As shown in fig. 1-2, the cathode heater of the microwave source includes a filament 110 in a spiral shape, and the filament 110 includes a first core 111 and a second core 112 disposed adjacent to each other in a radial direction. The cathode heater works in the first magnetic field B, when the first core 111 and the second core 112 are electrified, the current directions of the first core 111 and the second core 112 are opposite, and the ampere force applied to the first core 111 and the second core 112 in the first magnetic field B is opposite. In some embodiments, the direction of the arrow in fig. 1 represents the direction of the first magnetic field, and the directions of the currents of the first core 111 and the second core 112 are shown as "●" and "x" in fig. 2. "●" indicates that the magnetic field is directed outward perpendicular to the page and "x" indicates that the magnetic field is directed inward perpendicular to the page. The relevant contents of the first magnetic field B will be explained in detail below. The shape of the cross section of the first core 111 and the second core 111 may be any shape, such as a circle, an ellipse, a rectangle, etc., which is not further limited in this application. Since the filament 110 includes the first core 111 and the second core 112 that are adjacently disposed in the radial direction of the spiral shape, and the current directions of the first core 111 and the second core 112 are opposite, the directions of the ampere forces that the first core 111 and the second core 112 receive in the radial direction in the first magnetic field are also opposite, and then by disposing the current directions in the first core 111 and the second core 112 (for example, by disposing the first core 111 and the second core 112 in specific current directions), the ampere forces that the first core 111 and the second core 112 receive in the first magnetic field can be opposite (but not opposite to each other), so that the ampere force that the first core 111 receives in the radial direction and the ampere force that the second core 112 receives in the radial direction can be partially or completely cancelled, and the ampere force that the filament 110 receives in the radial direction as a whole can be partially or completely cancelled.

In some embodiments, the first core 111 and the second core 112 may be cores of two different wires (filaments), and both ends of the first core 111 and the second core 112 are respectively connected to a power supply to supply power to the two cores. In other embodiments, the first core 111 and the second core 112 may be cores of different portions of the same wire (filament). For example, after a wire is wound into a spiral shape to form a first spiral cylinder, the wire is bent, and a second spiral cylinder is further wound along the first spiral cylinder in the opposite direction. Contained within the first helical cylinder is a first core 111 and contained within the second helical cylinder is a second core 112. In this case, when the wire is energized, the currents in the first core 111 and the second core 112 are equal in magnitude and opposite in direction. For another example, the first core 111 and the second core 112 are two cores juxtaposed in the same wire, that is, seemingly one wire, but the first core 111 and the second core 112 juxtaposed can be seen by cutting a cross section of the wire. At this time, although seemingly a spiral cylinder, the spiral portion corresponding to the first core 111 is regarded as the first spiral cylinder, and the spiral portion corresponding to the second core 112 is regarded as the second spiral cylinder. In any embodiment of the present invention, the space between the first core 111 and the second core 112 is filled with an insulating material.

In some embodiments, the coiled filament 110 may include only one core, and when the filament 110 is energized, the cathode heater operates in the first magnetic field, and under the action of ampere force, the coiled filament 110 may expand or contract radially outward or inward (specifically, outward or inward, depending on the direction of the first magnetic field and the direction of current flow), and the coiled filament 110 may have a tendency to expand or contract radially outward, which may cause damage to the filament or to an insulating layer (e.g., a ceramic layer) that is wrapped around the filament. This may shorten the life of the filament 110 and thus the cathode heater and cathode.

The first magnetic field B represents the magnetic field in the environment in which the spiral filament 100 is located, which has a certain strength and direction. The direction of the first magnetic field can be chosen in many ways. In some embodiments, the direction of the first magnetic field is parallel to the axial direction of the coiled filament 110. In other embodiments, the direction of the first magnetic field may be at an angle, such as 10 °, 15 ° or 30 °, to the axial direction of the coiled filament 110. In other embodiments, the coiled filament 100 may be in an environment with other magnetic fields having different strengths and directions than the first magnetic field; alternatively, the first magnetic field may be considered as a partial component of a certain magnetic field.

In some embodiments, the first core 111 is helically wound to form a first helical cylinder and the second core 112 is helically wound to form a second helical cylinder, the first helical cylinder having a diameter less than the diameter of the second helical cylinder. That is, the first core 111 is provided inside the second core 112 in the radial direction (the radial direction of the cylinder formed by the spiral filament), and the first core 111 and the second core 112 are juxtaposed everywhere. In some embodiments, the first core 111 is exposed to a first ampere force in a first magnetic field in a radially outward direction and the second core 112 is exposed to a second ampere force in the first magnetic field in a radially inward direction, on any cross-section perpendicular to the axis of the coiled filament 110. With such an arrangement, the filament 110 is simpler and more convenient to manufacture, and the radial forces experienced by the various portions of the filament 110 can be reduced or even completely cancelled.

In some embodiments, it may be ensured that the currents flowing in the first core 111 and the second core 112 are equal in magnitude and opposite in direction. For example, when the first core 111 and the second core 112 are cores of two different wires (filaments), the first core 111 and the second core 112 may be electrically connected (e.g., end-to-end) such that the currents in the two are equal in magnitude and opposite in direction. Alternatively, the first core 111 and the second core 112 may be insulated from each other, and power is supplied to the first core 111 and the second core 112 respectively, and it is ensured that currents in the two cores are equal and opposite in direction. For another example, the first core 111 and the second core 112 may be cores of different parts of the same wire (filament), so as to ensure that the currents flowing through the first core 111 and the second core 112 are equal in magnitude and opposite in direction. In some embodiments, when the first core 111 and the second core 112 correspond to two different wires (filaments), the cross-sectional areas of the first core 111 and the second core 112 may be the same. At this time, since the lengths of the first core 111 and the second core 112 are different, the voltages applied to the first core 111 and the second core 112 are different. In other embodiments, the cross-sectional areas of the first core 111 and the second core 112 may also be different. By arranging the first core 111 and the second core 112 in the same and opposite directions, the ampere forces applied to the first core 111 and the second core 112 in the first magnetic field are opposite and equal, the ampere forces applied to the first core 111 and the second core 112 in the radial direction of the spiral can be completely cancelled, and the spiral filament 110 can be entirely free from the radial force.

In some embodiments, the filament 110 may be made of a material having a high melting point (e.g., > 1110℃.) and being electrically conductive. For example, the filament 110 may be made of at least one material of tungsten, molybdenum, rhenium, and iridium.

In some embodiments, the cathode heater further comprises an insulating support layer 120, and the filament 111 is embedded in the insulating support layer 120. The insulating support layer 120 can protect and support the filament 110 and improve structural stability of the cathode heater. In some embodiments, the first core 111 and the second core 112 may be embedded in the insulating support layer 120, respectively, such that the first core 111 and the second core 112 are separated by the insulating support layer 120. After the first core 111 and the second core 112 are separated by the insulating support layer, mutual interference between the first core 111 and the second core 112 can be effectively avoided, and stable operation of the cathode heater is ensured. Exemplary materials of the insulating support layer 120 may include mica, ceramic, etc., or any combination thereof. In some embodiments, the cross-section of the insulating support layer 120 may have any shape, such as circular, oval, rectangular, and the like.

The cathode heater disclosed in the embodiments of the present application may have the following advantages, including but not limited to: (1) the ampere force in the radial direction borne by the first core and the second core in the first magnetic field can be completely or partially offset, the ampere force borne by the filament in the radial direction is reduced as a whole, the filament can even be completely free from the ampere force, and the service life of the cathode heater is prolonged; (2) the heating power of the spiral filament is higher, and the heating effect is better; (3) the cathode heater is simple and convenient to manufacture; (4) the structure of the cathode heater is more stable. It is to be noted that different embodiments may produce different advantages, and in different embodiments, any one or combination of the above advantages may be produced, or any other advantages may be obtained.

FIG. 3 is a schematic diagram of a cathode heater of a microwave source according to further embodiments of the present application. As shown in fig. 3, the cathode heater operates in a first magnetic field B; the cathode heater includes one or more lamp posts 210, and a length direction of the one or more lamp posts 210 is parallel to a direction of the first magnetic field. When the lamp posts 210 are multiple, the lamp posts 210 are arranged in parallel. The relevant contents of the first magnetic field B will be explained in detail below. The current directions of the plurality of lamp posts 210 may be the same, and the current directions of any two lamp posts 210 in the plurality of lamp posts 210 may be opposite. The shape of the cross-section of the lamp post 210 may be any shape, such as circular, annular, oval, rectangular, etc. Compared with the spiral filament only comprising one core, the filament is changed into the lamppost 210 with the length direction parallel to the direction of the first magnetic field B, the lamppost 210 can not be subjected to ampere force any more, the lamppost 210 cannot deform, and the service life of the cathode heater and the cathode is prolonged. When the lamp post is multiple, the heating power of the cathode heater can be improved.

The first magnetic field B may be understood as a magnetic field having a certain strength and a certain direction. In other embodiments, other magnetic fields having different strengths and directions from the first magnetic field B may also be provided; alternatively, the first magnetic field may be a partial component of a certain magnetic field. The lamppost 210 is not subject to an ampere force under the influence of the first magnetic field when operating in the first magnetic field B.

As shown in fig. 3, in some embodiments, to increase the heating power of the cathode heater, the cathode heater includes a plurality of lamp posts 210 (e.g., 2, 6, 8, etc.), and the plurality of lamp posts 210 are spaced apart from each other. The cross-sectional areas and shapes of the plurality of lamp posts 210 may be the same, so that the resistances of the plurality of lamp posts 210 have the same magnitude, and when voltages having the same magnitude are applied to the lamp posts 210, currents flowing through the plurality of lamp posts 210 have the same magnitude. In some embodiments, the plurality of lampposts 210 may be arranged along a circumferential direction. The number of lamp posts 210 can be specifically determined by those skilled in the art according to the design requirements of the cathode heater, for example, when the heating power of the cathode heater is required to be larger, the number of lamp posts 210 can be increased.

Fig. 4 is a schematic diagram of a radial cross-section of an annular lamppost of a cathode heater of a microwave source according to further embodiments of the present application. In some embodiments, as shown in fig. 4, the cathode heater includes a lamp post 210, and the lamp post 210 is an annular lamp post 211. By designing the lamp post 210 to be ring-shaped, the heating power of the cathode heater can be increased. And the structural stability of annular lamp pole 211 is higher, can need not to set up other bearing structure and support annular lamp pole 211.

In some embodiments, the cathode heater further includes a first wiring member 220 and a second wiring member 230, both ends of the lamp post 210 are fixed to the first wiring member 220 and the second wiring member 230, respectively, and both ends of the lamp post 210 are connected to a power source through leads, respectively. The first and

second wire members

220 and 230 may serve to support and fix the lamp post 210 and may also facilitate connection of the lamp post with a power source.

In some embodiments, the lamppost 210 may be made of a material that has a high melting point (e.g., > 1000 ℃) and is electrically conductive. For example, the lamppost 210 may be made of at least one material of tungsten, molybdenum, rhenium, and iridium.

In some embodiments, the cathode heater further comprises an insulating support layer (not shown) in which the lamp post 210 is embedded. Exemplary materials for the insulating support layer may include mica, ceramic, etc., or any combination thereof. A person skilled in the art can determine whether to provide an insulating support layer according to the actual situation of the lamppost 200, for example, when the lamppost 210 is thick, the structural strength of the lamppost 210 itself is large, and the insulating support layer may not be provided; when the lamp post 210 is thin, an insulating support layer may be provided to support the lamp post 210. The cross section of the insulating support layer can be in any shape, such as a circle, an ellipse, a rectangle, and the like.

The cathode heater disclosed in the embodiments of the present application may have beneficial effects including, but not limited to: (1) the length direction of the lamp post is parallel to the direction of the first magnetic field, the lamp post cannot deform under the action of the ampere-power force in the first magnetic field, and the service life of the cathode heater is prolonged; (2) the heating power of the cathode heater can be conveniently changed by changing the number of the lamp posts; (3) the structure of the cathode heater is more stable. It is to be noted that different embodiments may produce different advantages, and in different embodiments, any one or combination of the above advantages may be produced, or any other advantages may be obtained.

Fig. 5 is a schematic view of an exemplary radiation therapy system shown in accordance with some embodiments of the present application. As shown in fig. 5, radiation therapy system 500 can include radiation therapy device 510, network 520, one or more terminals 530, processing device 540, and storage device 550.

The radiation treatment device 510 may deliver a beam of radiation to a target object (e.g., a patient or phantom). In some embodiments, radiation therapy device 510 may include a linear accelerator (also referred to as a "linac") 511. Linac 511 may generate and emit a radiation beam (e.g., an X-ray beam) from treatment head 512. The radiation beam may pass through one or more collimators of a particular shape (e.g. a primary collimator and/or a multi-leaf collimator (MLC)) and then enter the target object. In some embodiments, the beam of radiation may comprise electrons, photons, or other types of radiation. In some embodiments, the energy of the radiation beam may be in the megavolt range (e.g., >1MeV), and thus may be referred to as a megavolt beam. The treatment head 511 may be coupled to a gantry 513. The gantry 513 may rotate clockwise or counterclockwise, for example, about a gantry rotation axis 514. The treatment head 512 may rotate with the gantry 513. In some embodiments, the radiation therapy device 510 can include an imaging element 515. The imaging element 515 may receive the radiation beam that has passed through the target object and generate an image of the patient and/or phantom before, during, and/or after a radiation therapy or correction procedure based on the received radiation beam. The imaging element 515 may include an analog detector, a digital detector, and the like, or a combination thereof. Imaging element 515 may be coupled to gantry 513 in any coupling manner, including an expandable housing. Thus, rotation of gantry 513 can cause treatment head 512 and imaging element 515 to rotate in unison. In some embodiments, the radiation therapy device 510 can also include a couch 516. The couch 516 may support a patient during radiotherapy or imaging, and/or a phantom during a calibration procedure of the radiotherapy device 510. The couch 516 may be adjusted to suit different application scenarios.

Network 520 may include any suitable network that facilitates the exchange of information and/or data for radiation treatment system 500. In some embodiments, one or more components of the radiation therapy system 500 (e.g., the radiation therapy device 510, the terminal 530, the processing device 540, the storage device 550, etc.) may communicate information and/or data with one or more other components of the radiation therapy system 500 via the network 520. For example, processing device 540 may obtain planning data from terminal 530 via network 520. The network 520 may be and/or include a public network (e.g., the internet), a private network (e.g., a Local Area Network (LAN), a Wide Area Network (WAN)), etc.), a wired network (e.g., an ethernet network, a wireless network (e.g., an 802.11 network, a Wi-Fi network, etc.), a cellular network (e.g., a Long Term Evolution (LTE) network), a frame relay network, a virtual private network ("VPN"), a satellite network, a telephone network, a router, a hub, a switch, etcA server computer, and/or any combination thereof. By way of example only, network 520 may include a cable network, a wireline network, a fiber optic network, a telecommunications network, an intranet, a Wireless Local Area Network (WLAN), a Metropolitan Area Network (MAN), a Public Switched Telephone Network (PSTN), Bluetooth, or the like^TMNetwork and ZigBee^TMA network, a Near Field Communication (NFC) network, etc., or any combination thereof. In some embodiments, network 520 may include one or more network access points. For example, network 520 may include wired and/or wireless network access points, such as base stations and/or internet exchange points, through which one or more components of radiation treatment system 500 may connect to network 520 to exchange data and/or information.

The terminal 530 may enable interaction between a user and the radiation therapy system 500. Terminal 530 may include a mobile device 531, a tablet computer 532, a laptop computer 533, etc., or any combination thereof. In some embodiments, the mobile device 531 may include a smart home device, a wearable device, a smart mobile device, a virtual reality device, an augmented reality device, and the like, or any combination thereof. In some embodiments, the smart home devices may include smart lighting devices, smart appliance control devices, smart monitoring devices, smart televisions, smart cameras, interphones, and the like, or any combination thereof. In some embodiments, the wearable device may include a bracelet, footwear, glasses, helmet, watch, clothing, backpack, smart accessory, and the like, or any combination thereof. In some embodiments, the mobile terminal may include a mobile phone, a Personal Digital Assistant (PDA), a gaming device, a navigation device, a point of sale (POS) device, a laptop, a tablet, a desktop, or the like, or any combination thereof. In some embodiments, the virtual reality device and/or the augmented reality device includes a virtual reality helmet, virtual reality glasses, virtual reality eyeshields, augmented reality helmets, augmented reality glasses, augmented reality eyeshields, and the like, or any combination thereof. For example, the virtual reality device and/or augmented reality device may include a Google Glass^TM、Oculus Rift^TM、Hololens^TM、Gear VR^TMAnd the like. In some embodiments, terminal 530 may be part of processing device 540。

The processing device 540 may process data and/or information obtained from the radiation treatment device 510, the one or more terminals 530, and/or the storage device 550. In some embodiments, the processing device 540 may perform one or more radiation therapy operations. For example, the processing device 540 may process planning data (e.g., from a Treatment Planning System (TPS)) and determine motion parameters that may be used to control motion of various components in the radiation therapy device 510. In some embodiments, processing device 540 may be a computer, a user console, a single server or group of servers, or the like. The server groups may be centralized or distributed. In some embodiments, the processing device 540 may be local or remote. For example, the processing device 540 may access information and/or data stored in the radiation therapy device 110, the terminal 130, and/or the storage device 550 via the network 520. As another example, the processing device 540 may be directly connected to the radiation therapy device 510, the terminal 530, and/or the storage device 550 to access stored information and/or data. In some embodiments, processing device 540 may be implemented on a cloud platform. By way of example only, the cloud platform may include a private cloud, a public cloud, a hybrid cloud, a community cloud, a distributed cloud, an internal cloud, a multi-tiered cloud, and the like, or any combination thereof.

Storage 550 may store data, instructions, and/or any other information. In some embodiments, storage device 550 may store data obtained from terminal 530 and/or processing device 540. In some embodiments, storage device 550 may store data and/or instructions that processing device 540 may perform or be used to perform the example methods described herein. In some embodiments, storage 550 may include mass storage, removable storage, volatile read-write memory, read-only memory (ROM), and the like, or any combination thereof. Exemplary mass storage devices may include magnetic disks, optical disks, solid state drives, and the like. Exemplary removable memory may include flash drives, floppy disks, optical disks, memory cards, compact disks, magnetic tape, and the like. Exemplary volatile read and write memory may include Random Access Memory (RAM). Exemplary RAM may include Dynamic Random Access Memory (DRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), Static Random Access Memory (SRAM), thyristor random access memory (T-RAM), and zero capacitance random access memory (Z-RAM), among others. Exemplary ROMs may include mask-type read-only memory (MROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM), digital versatile disc read-only memory, and the like. In some embodiments, the storage device 150 may execute on a cloud platform. By way of example only, the cloud platform may include a private cloud, a public cloud, a hybrid cloud, a community cloud, a distributed cloud, an internal cloud, a multi-tiered cloud, and the like, or any combination thereof.

In some embodiments, the storage device 550 may be connected to the network 520 to communicate with one or more other components in the radiation therapy system 500 (e.g., the processing device 540, the terminal 530, etc.). One or more components in radiation treatment system 500 may access data or instructions stored in storage device 550 through network 520. In some embodiments, the storage device 550 may be directly connected to or in communication with one or more other components in the radiation therapy system 500 (e.g., the processing device 540, the terminal 530, etc.). In some embodiments, the storage device 550 may be part of the processing device 540. In some embodiments, the processing device 540 may be connected to or in communication with the radiation therapy device 510 via the network 520 or at the back end of the processing device 540.

FIG. 6 is a schematic diagram of exemplary components of a linear accelerator (linac) shown in accordance with some embodiments of the present application. In some embodiments, the linear accelerator 600 shown in fig. 6 may be implemented on a radiation therapy device (e.g., radiation therapy device 510). As shown in fig. 6, the linac 600 may include a power supply 602, a modulator 604, an electron generator 606, a microwave source 608, an accelerator tube 610, and a treatment head 612. In some embodiments, the power supply 602 may be used to provide the high voltage (e.g., 45kV) needed for proper modulator operation. In some embodiments, the power supply 602 may include an Alternating Current (AC) circuit for providing an AC voltage (ACV). In some embodiments, the power supply 602 may include a Direct Current (DC) circuit for providing a Direct Current Voltage (DCV). The modulator 604 may be used to simultaneously provide high voltage pulses (e.g., DC pulses) to the electron generator 606 and the microwave source 608. An electron generator 606 (e.g., an electron gun or electron emitter) may generate electrons that are injected into the acceleration tube 610. For example, the electron generator 606 may generate electrons along a range of angles and emit the electrons along a beam path. The electron beam may be injected into the acceleration tube 610. The acceleration tube 610 may be used to accelerate electrons emitted by the electron generator 606 in response to microwaves generated by the microwave source 608. That is, with microwaves of one or more frequency ranges, electrons in the accelerator tube 610 may be accelerated in one or more kinetic energy ranges. The accelerated electrons may be transmitted to treatment head 612 to generate a radiation beam. For example, the accelerated electrons may strike a target (e.g., an X-ray target) to generate a radiation beam (e.g., an X-ray beam). The radiation beam may pass through one or more collimators of a particular shape (e.g. a primary collimator and/or a multi-leaf collimator (MLC)) to form a collimated radiation beam. The collimated beam of radiation may illuminate a target object (e.g., a lesion of a subject) to deliver radiation therapy.

In some embodiments, the microwave source 608 may be configured to generate microwaves within one or more frequency ranges. The microwave source 608 may be considered an oscillator that converts the DC pulses from the modulator 604 into microwave pulses. In some embodiments, the microwave source 608 may be a magnetron or a klystron. In some embodiments, the microwave source 608 may include a magnetron (also referred to as a single cathode magnetron) comprised of one cathode and one anode block. In some embodiments, the microwave source 608 may include a magnetron (also referred to as a multi-cathode magnetron) comprised of a plurality of cathodes and an anode block. Multiple cathodes may share the same anode block. The microwave source 608 may output different microwave powers through different arrangements of cathode and anode blocks.

In some embodiments, the microwave source 608 may be a magnetron. In a magnetron, the cathode may be heated by a cathode heater. The cathode heater may include at least one filament. Electrons released from the cathode may be accelerated toward the anode mass by the action of a pulsed dc electric field. The anode block may comprise at least two resonant cavities. In some embodiments, at least one electromagnet may be placed around the anode block. The static magnetic field may be applied perpendicular to a cross section of the at least two resonant cavities. Due to the influence of the magnetic field, the released electrons may move in a complex spiral towards the resonant cavity. When the cavity starts to resonate at a certain resonance frequency (e.g., 3000MHz), a resonance effect (or resonance phenomenon) may occur. The cavity can then emit microwaves. The microwaves may be transmitted to the accelerating tube 610 through a transmission waveguide. Electrons in the accelerating tube 610 may be accelerated by microwave energy. More description of the microwave source assembly can be found elsewhere in this application (e.g., fig. 1-4 and 7A-9 and their descriptions).

Fig. 7A is a cross-sectional view of an exemplary microwave source (e.g., magnetron) shown in accordance with some embodiments of the present application. As shown in fig. 7A, the microwave source 700 may include an anode block 710 and a cathode 720 located at the center of the anode block 710. The anode block 710 and the cathode 720 may be coaxial. In some embodiments, the anode block 710 may be fabricated as a cylindrical metal block (e.g., a copper block). The anode block 710 may include at least two resonant cavities 712. The number of resonant cavities may be different for different microwave sources. In some embodiments, the number of resonant cavities may be between 8 and 20. For illustration purposes only, the anode block 710 includes eight resonant cavities 712, i.e., eight cylindrical holes around the cathode 720. An interaction space may be formed between the anode block 710 and the cathode 720, such as an open space between the anode block 710 and the cathode 720. In some embodiments, the microwave source further comprises a magnetic circuit assembly (not shown) for generating the first magnetic field. In the interaction space, an electric field and a magnetic field (e.g., a first magnetic field) interact to exert a force on the electrons. In some embodiments, the magnetic circuit assembly may comprise a core and an electromagnet, by which the strength of the first magnetic field may be conveniently varied. In other embodiments, the magnetic circuit assembly may include a permanent magnet. The magnetic field (e.g., the first magnetic field) may be provided by a permanent magnet mounted around the microwave source 700 so that the magnetic field is parallel to the axis of the cathode. Electrons released from the cathode 720 may propagate outward in the interaction space. The released electrons can be accelerated towards the anode block 710 by the action of the pulsed dc electric field. Due to the magnetic field, electrons may move in a complex spiral towards the resonant cavity 712. In some embodiments, the resonant cavity 712 may exist in various shapes, including, for example, but not limited to, a semi-circular cavity, a square cavity, a rectangular cavity, a fan-shaped cavity, or any combination thereof.

FIG. 7B is a different form of an anode block in a microwave source according to some embodiments of the present application. As shown in fig. 7B, the anode block 710a may include at least two holes and groove type resonant cavities 712a, the anode block 710B may include at least two groove type resonant cavities 712B, and the anode block 710c may include at least two blade type resonant cavities 712 c. The cavities are typically distributed in a radial direction.

Fig. 7C is an exemplary profile of a cathode of a microwave source according to some embodiments of the present application. As shown in fig. 7C, the cathode 720 may include a hollow dumbbell structure. In some embodiments, the cathode 720 may be comprised of a hollow cylinder of emissive material (e.g., barium oxide) surrounding the cathode heater. For example, the cathode 720 may include a cathode heater and a thermionic emitter. The cathode heater may include at least one filament. The thermionic electron emitter may consist of a hollow cylinder of emissive material. In some embodiments, a cathode heater with a coiled filament 110 as described in the previous embodiments of the present application may be used (see the associated description of FIGS. 1-2). In other embodiments, a cathode heater having one or more lamp posts 210 as described in the above embodiments of the present application may also be used (see the associated description of fig. 3-4). In other embodiments, the cathode heater may be fixed to the cathode support member (e.g., cathode rod) in a spiral. The cathode support element may be positioned in the hollow space of the thermionic electron emitter. When the cathode heater is heated by a power supply, the external thermionic electron emitter releases electrons due to thermions generated by thermal radiation. The electrons thus released can move outward toward the anode block. When the electrons pass through the resonant cavity of the anode block, energy can be transferred to the resonant cavity, which can then resonate at a certain resonant frequency and radiate the energy in the form of microwaves.

Fig. 8 is a cross-sectional view of an exemplary microwave source shown in accordance with some embodiments of the present application. The microwave source 800 shown in fig. 8 may be a magnetron for illustration purposes only. The magnetron may be a tunable magnetron. The microwave source 800 may include an anode block 802, a cathode 804 located at the center of the anode block 802, a tuning element 806, a microwave follower 808, and a transmission waveguide 810. As described in connection with fig. 7A and 7B, the anode block 802 may include at least two resonant cavities 802 a. The resonant cavity 802a may exist in the form of holes and grooves as shown in fig. 7B. The cathode 804 may be movably positioned in the center of the anode block. The cathode 804 may include a cathode heater, the details of which are described in relation to figures 1-4, for example. Further description of the anode block and cathode may be found elsewhere in this application (e.g., fig. 7A-7C and their description), and will not be repeated here.

The tuning element 806 may be configured to adjust the resonant frequency of the microwave source 800. The resonant frequency can be changed by changing the inductance or capacitance of the microwave source cavity. In some embodiments, the tuning element 806 may be inserted into the aperture and the aperture of the groove cavity. The tuning element 806 can change the capacitance of the resonant cavity by changing the ratio of surface area to cavity volume in the high current region. The resonant frequency of the microwave source 800 may be tuned up or down by inserting or removing the tuning element 806. For example, when the tuning element 806 is inserted into the anode hole, the capacitance of the cavity may be increased, and thus the resonant frequency may be decreased. In some embodiments, the microwave source 800 may include a plurality of tuning elements 806 operatively connected to each resonant cavity 802 a. Only one tuning element 806 is shown for illustrative purposes only. In some embodiments, the tuning element 806 may be made of a conductive material (e.g., copper, aluminum, or other metallic material).

The microwave follower 808 may be used to transmit microwaves generated by a microwave source. The microwaves may be transmitted into a transmission waveguide (e.g., the transmission waveguide shown in fig. 6). The transmission waveguide may then transmit the microwaves to an acceleration tube (e.g., an acceleration tube) to provide kinetic energy to accelerate electrons in the acceleration tube.

Fig. 9 is a cross-sectional view of an exemplary microwave source shown in accordance with some embodiments of the present application. As shown in fig. 9, the microwave source 900 may be a multi-cathode microwave source (e.g., a multi-cathode magnetron). The microwave source 900 may include an anode block 902 and a plurality of cathodes, such as a first cathode 904 and a second cathode 906. In some embodiments, a plurality of cathodes may be movably positioned in the center of the anode block 902.

In some embodiments, the diameters of the plurality of cathodes may be different. In some embodiments, at least two cathodes of the plurality of cathodes may differ in diameter. For example, the first cathode diameter may be 18 millimeters and the second cathode diameter may be 22 millimeters. In some embodiments, the microwave source 900 may include a connector 908. The plurality of cathodes may be mechanically coupled to each other by a connector 908. A connector 908 (e.g., a support rod) may be used to support and connect each cathode. The connector 908 may be made of an insulating material. In some embodiments, microwave source 900 may include a stop member 910. One end of the connector 908 may be operatively connected to a stop member 910. In some embodiments, the microwave source 900 may include a guide slot 912. Stop member 910 may be disposed in guide groove 912. In some embodiments, stop member 910 can be moved (e.g., slid) along guide groove 912 to position a cathode of the plurality of cathodes. For example, when the stop member 910 is moved to the first position, the first cathode 904 may be positioned at the center of the anode block. When the stop member 910 is moved to the second position, the second cathode 906 may be positioned in the center of the anode block 902 and the first cathode 904 may be removed. In some embodiments, stop member 910 may be driven by a variety of drive devices. Exemplary drive devices may include hydraulic drives, pneumatic drives, electric actuators. In some embodiments, the various driving devices may not interfere with the generation of microwaves.

The electron efficiency of a microwave source (e.g., magnetron) may depend on the ratio of the diameters of the cathode and anode blocks (also referred to as the "diameter ratio"). When the diameter ratio is within a specific range, the electron efficiency may be at an optimum value and the output power of the microwave source may be maximized. For example, for an eight-cavity anode block, the electron efficiency of the magnetron may be optimal when the diameter ratio is in the range of 0.37-0.42. As another example, for a ten-two-cavity anode block, the electron efficiency of the magnetron may be optimal when the diameter ratio is in the range of 0.50-0.58. As another example, for a sixteen-cavity anode block, the electron efficiency of the magnetron may be optimal when the diameter ratio is in the range of 0.60-0.66.

In some embodiments, the output power of the microwave source may be varied by varying the diameter ratio of the anode block to the cathode. In some embodiments, the diameter ratio can be varied by alternating cathodes having different diameters for a particular anode block. For illustration only, the resonant frequency is 2998MHz and the maximum output power is 3.4MW for a magnetron comprising a ten two-cavity anode block. The anode block is assumed to be 34 mm in diameter. The maximum output power of the magnetron can only be achieved when the diameter of the cathode is in the range of 17-19.72 mm. It is understood that the magnetron can output relatively small microwave power when the diameter of the cathode is less than 17 mm or more than 19.72 mm. By providing a fixed anode block and cathodes having different diameters, the magnetron can output variable microwave power. Variable microwave power may be used to generate radiation beams of different energies. For example, the diameter of the anode block 902 may be set to 34 mm, and the diameter of the first cathode may be set to 18 mm. The microwave source may output a maximum microwave power for accelerating electrons in the acceleration tube to produce a therapeutic radiation beam when the anode block and the first cathode are energized. The therapeutic radiation beam may be for ablating tumorous tissue of the target object. For another example, the diameter of the second cathode may be set to 22 mm. When the anode block and the second cathode are energized, the microwave source may output relatively less microwave power to accelerate electrons in the acceleration tube to generate a beam of imaging radiation. For IGRT devices, the imaging radiation beam may be used to image a region of interest (ROI) in relation to the target object. The radiation therapy procedure can be guided according to information related to the ROI (e.g., tumor region).

In some embodiments, the resonant frequency of the microwave source can be varied by alternating the different cathodes. The resonant frequency of the microwave source may depend on the equivalent capacitance and inductance of the microwave source. For example, the resonant frequency

Where L represents inductance and C represents equivalent capacitance. For a fixed anode block, the larger the diameter of the cathode, the smaller the distance between the cathode and the anode block, and thus the larger the equivalent capacitance becomes. The resonant frequency may vary with the equivalent capacitance. In some embodiments, by switching cathodes of different diameters, different resonant frequencies can be generated accordingly. In addition, a tuning element (e.g., tuning element 806) of the microwave source may fine tune the resonant frequency, e.g., ± 5 MHz. By using the plurality of cathodes and the tuning element, the tunable range of the resonant frequency of the microwave source can be extended. It will be appreciated that the output frequency of the microwaves may vary with the characteristics (e.g., resonant frequency) of the microwave source. When different cathodes are applied, a specific microwave frequency can be generated.

Having thus described the basic concepts, it will be apparent to those of ordinary skill in the art having read this application that the foregoing disclosure is to be construed as illustrative only and is not limiting of the application. Various modifications, improvements and adaptations of the present application may occur to those skilled in the art, although they are not explicitly described herein. Such modifications, improvements and adaptations are proposed in the present application and thus fall within the spirit and scope of the exemplary embodiments of the present application.

Also, this application uses specific language to describe embodiments of the application. For example, "one embodiment," "an embodiment," and/or "some embodiments" means that a particular feature, structure, or characteristic described in connection with at least one embodiment of the application. Therefore, it is emphasized and should be appreciated that two or more references to "an embodiment" or "one embodiment" or "an alternative embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, certain features, structures, or characteristics of one or more embodiments of the application may be combined as appropriate.

Additionally, the order in which elements and sequences of the processes described herein are processed, the use of alphanumeric characters, or the use of other designations, is not intended to limit the order of the processes and methods described herein, unless explicitly claimed. While various presently contemplated embodiments of the invention have been discussed in the foregoing disclosure by way of example, it is to be understood that such detail is solely for that purpose and that the appended claims are not limited to the disclosed embodiments, but, on the contrary, are intended to cover all modifications and equivalent arrangements that are within the spirit and scope of the embodiments herein. For example, although an implementation of the various components described above may be embodied in a hardware device, it may also be implemented as a pure software solution, e.g., installed on an existing server or mobile device.

Similarly, it should be noted that in the preceding description of embodiments of the application, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure aiding in the understanding of one or more embodiments of the invention. This method of application, however, is not to be interpreted as reflecting an intention that the claimed subject matter to be scanned requires more features than are expressly recited in each claim. Rather, the inventive body should possess fewer features than the single embodiment described above.

Claims

1. A cathode heater of a microwave source is characterized by comprising a filament in a spiral shape, wherein the filament comprises a first core body and a second core body which are adjacently arranged along the radial direction of the spiral shape;

the cathode heater works in a first magnetic field, when the first core and the second core are electrified, the current directions of the first core and the second core are opposite, and the ampere force applied to the first core and the second core in the first magnetic field is opposite.

2. The cathode heater of a microwave source of claim 1 wherein the direction of the first magnetic field is parallel to the axial direction of the coiled filament.

3. The cathode heater of a microwave source of claim 2 wherein the first core is helically wound to form a first helical cylinder and the second core is helically wound to form a second helical cylinder, the first helical cylinder having a diameter less than the diameter of the second helical cylinder;

on any cross-section perpendicular to the axis of the coiled filament, the first core is subjected to a first ampere force in the first magnetic field in a direction radially outward, and the second core is subjected to a second ampere force in the first magnetic field in a direction radially inward.

4. The cathode heater of a microwave source of claim 1 wherein the first core and the second core are filled with an insulating material therebetween.

5. The microwave source cathode heater of claim 1 further comprising an insulating support layer, the filament being embedded in the insulating support layer.

6. The cathode heater of a microwave source of claim 1 wherein the first core and the second core are configured to form a same filament; alternatively, the first core and the second core are configured to form two filaments.

7. The cathode heater of a microwave source of claim 1 wherein the first core and the second core have equal current values.

8. A cathode heater for a microwave source, wherein the cathode heater operates in a first magnetic field; the cathode heater comprises one or more lampposts, and the length direction of the one or more lampposts is parallel to the direction of the first magnetic field.

9. The cathode heater of a microwave source of claim 8 wherein the cathode heater comprises a lamp post, the lamp post being an annular lamp post; alternatively, the cathode heater comprises a plurality of lamp posts.

10. The cathode heater of a microwave source as claimed in claim 8, further comprising a first wiring member and a second wiring member, both ends of the lamp post being fixed to the first wiring member and the second wiring member, respectively, and both ends of the lamp post being connected to a power source through leads, respectively.

11. The microwave source cathode heater of claim 8 further comprising an insulating support layer in which the lamp post is embedded.

12. A cathode for a microwave source, comprising a cathode heater for a microwave source according to any one of claims 1 to 11;

the cathode further includes a thermionic electron emitter configured to release electrons when heated by the cathode heater.

13. A radiotherapy apparatus comprising a linear accelerator, characterized in that the linear accelerator comprises:

an electron generator for emitting electrons;

a microwave source for generating microwaves, the microwave source comprising an anode block and a cathode, the cathode comprising a cathode heater of the microwave source of any one of claims 1 to 11;

an accelerating tube for accelerating electrons emitted by the electron generator in response to the microwaves.