Patent Description:
Radiation therapy is widely used in cancer treatment and is also beneficial to several other health conditions. A radiotherapy device (e.g., a linear accelerator) is often utilized to perform the radiation therapy. In the radiotherapy device, a microwave source, composed of an anode and a cathode, is configured to produce microwave pulses (or radio frequency pulses) for controlling the generation of radiation beams (e.g., X-rays). IN this context, document <CIT> is referred to. The microwave source is an important component for the radiotherapy device. In some cases, the cathode of the microwave source breaks easily due to frequent deformation of the cathode heater, and such malfunction often affects the normal use of the radiotherapy device. Therefore, it is desirable to develop a high-quality microwave source used in the radiotherapy device.

In particular, a multiple cathodes microwave source is provided. The cathode includes a cathode support element having a plurality of slots and a cathode heater including at least one filament. The plurality of slots are disposed axially around a circumference of the cathode support element. A first part of the at least one filament is wound around the cathode support element along a first direction and received by a first portion of the plurality of slots, and a second part of the at least one filament is wound around the cathode support element along a second direction and received by a second portion of the plurality of slots.

In some embodiments, the first part of the at least one filament and the second part of the at least one filament may be substantially parallel, and when the at least one filament is powered by a power source, directions of respective current flows of the first part and the second part of the at least one filament may be inversed.

In some embodiments, the first portion of the plurality of slots and the second portion of the plurality of slots may be spaced axially around the circumference of the cathode support element.

In some embodiments, a depth of a slot of the plurality of slots may be greater than or equal to a diameter of one of the at least one filament, and a width of the slot may be greater than or equal to the diameter of the filament.

In some embodiments, the diameter of the filament may be in a range of <NUM> to <NUM>.

In some embodiments, the at least one filament may be made of a high-melting-point and conductive material.

In some embodiments, the at least one filament may include at least one of tungsten, molybdenum, rhenium, or iridium.

In some embodiments, the cathode support element may be made of an insulative material.

In some embodiments, the cathode support element may include at least one of plastic, rubber, glass, ceramic.

In some embodiments, the cathode may include a thermionic emitter configured to release electrons when the thermionic emitter is heated by the cathode heater.

The microwave source includes an anode block and a cathode centered in the anode block. The cathode includes a cathode support element having a plurality of slots and a cathode heater including at least one filament. The plurality of slots is arranged axially around a circumference of the cathode support element. A first part of the at least one filament is wound around the cathode support element along a first direction and received by a first portion of the plurality of slots, and a second part of the at least one filament is wound around the cathode support element along a second direction and received by a second portion of the plurality of slots. In some embodiments, the first part of the at least one filament and the second part of the at least one filament may be substantially parallel, and when the at least one filament is powered by a power source, directions of respective current flows of the first part and the second part of the at least one filament may be inversed.

In a third aspect of the present disclosure, a radiotherapy device can be provided. The radiotherapy device may include a linear accelerator. The linear accelerator may include an electron generator configured to emit electrons along a beam path, a microwave source configured to generate microwaves and an accelerator tube configured to accelerate the electrons emitted by the electron generator in response to the microwaves. The microwave source includes an anode block and a cathode centered in the anode block. The cathode includes a cathode support element having a plurality of slots and a cathode heater including at least one filament. The plurality of slots is disposed axially around a circumference of the cathode support element. A first part of the at least one filament is wound around the cathode support element along a first direction and received by a first portion of the plurality of slots, and a second part of the at least one filament is wound around the cathode support element along a second direction and received by a second portion of the plurality of slots.

The microwave source includes an anode block and multiple cathodes. When an individual cathode of the multiple cathodes is removably positioned in a center of the anode block, microwaves having a specific frequency are generated in response to an occurrence of a resonance effect caused by the anode block and the cathode.

Diameters of at least two of the multiple cathodes are different.

In a fifth aspect of the present disclosure, a radiotherapy device can be provided. The radiotherapy device may include a linear accelerator. The linear accelerator may include an electron generator configured to emit electrons along a beam path and a microwave source configured to generate microwaves. The microwave source may include an anode block and multiple cathodes. When an individual cathode of the multiple cathodes is removably positioned in a center of the anode block, microwaves having a specific frequency may be generated in response to an occurrence of a resonance effect caused by the anode block and the cathode.

In some embodiments, the radiotherapy device may include an accelerator tube configured to accelerate the electrons emitted by the electron generator in response to the microwaves having the specific frequency.

In the following detailed description, numerous specific details are set forth by way of examples in order to provide a thorough understanding of the relevant disclosure. However, it should be apparent to those skilled in the art that the present disclosure may be practiced without such details. In other instances, well-known methods, procedures, systems, components, and/or circuitry have been described at a relatively high-level, without detail, in order to avoid unnecessarily obscuring aspects of the present disclosure. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the scope of the present disclosure. Thus, the present disclosure is not limited to the embodiments shown, but to be accorded the widest scope consistent with the claims.

It will be understood that the term "system," "engine," "unit," "module," and/or "block" used herein are one method to distinguish different components, elements, parts, section or assembly of different level in ascending order. However, the terms may be displaced by another expression if they may achieve the same purpose.

Generally, the word "module," "unit," or "block," as used herein, refers to logic embodied in hardware or firmware, or to a collection of software instructions. A module, a unit, or a block described herein may be implemented as software and/or hardware and may be stored in any type of non-transitory computer-readable medium or another storage device. In some embodiments, a software module/unit/block may be compiled and linked into an executable program. It will be appreciated that software modules can be callable from other modules/units/blocks or from themselves, and/or may be invoked in response to detected events or interrupts. Software modules/units/blocks configured for execution on computing devices may be provided on a computer-readable medium, such as a compact disc, a digital video disc, a flash drive, a magnetic disc, or any other tangible medium, or as a digital download (and can be originally stored in a compressed or installable format that needs installation, decompression, or decryption prior to execution). Such software code may be stored, partially or fully, on a storage device of the executing computing device, for execution by the computing device. Software instructions may be embedded in firmware, such as an Erasable Programmable Read Only Memory (EPROM). It will be further appreciated that hardware modules/units/blocks may be included in connected logic components, such as gates and flip-flops, and/or can be included of programmable units, such as programmable gate arrays or processors. The modules/units/blocks or computing device functionality described herein may be implemented as software modules/units/blocks, but may be represented in hardware or firmware. In general, the modules/units/blocks described herein refer to logical modules/units/blocks that may be combined with other modules/units/blocks or divided into sub-modules/subunits/sub-blocks despite their physical organization or storage. The description may be applicable to a system, an engine, or a portion thereof.

It will be understood that when a unit, engine, module or block is referred to as being "on," "connected to," or "coupled to," another unit, engine, module, or block, it may be directly on, connected or coupled to, or communicate with the other unit, engine, module, or block, or an intervening unit, engine, module, or block may be present, unless the context clearly indicates otherwise.

The following description is provided with reference to exemplary embodiments that a medical device includes a microwave source (e.g., a magnetron) unless otherwise stated. However, it is understood that it is for illustration purposes only and not intended to limit the scope of the present disclosure. The microwave source disclosed herein may be suitable for other applications (e.g., a microwave oven, a particle accelerator, etc.). Merely by way of example, the medical device may include a radiotherapy device, such as an image-guided radiotherapy (IGRT) device. The IGRT device may include an imaging component (e.g., MRI device, PET device, or CT device) and a radiation therapy component (e.g., a linear accelerator).

Various embodiments provided herein with reference to a microwave source composed of an anode block and one or more cathodes. In some embodiments, the microwave source (e.g., a single-cathode microwave source) may include an anode block and a cathode centered in the anode block. In some embodiments, the microwave source (e.g., a multi-cathode microwave source) may include an anode block and multiple cathodes. The multiple cathodes may share the same anode block. In some embodiments, one of the multiple cathodes can be removably positioned in the center of the anode block. Diameters of the multiple cathodes may be different. In response to an occurrence of a resonance effect caused by the anode block and the cathode, microwaves having a specific frequency may be generated. For example, when a first cathode is positioned in the anode block, first microwaves having a first frequency may be generated due to the resonant effect caused by the anode block and the first cathode. As another example, when a second cathode is positioned in the anode block, second microwaves having a second frequency may be generated due to the resonant effect caused by the anode block and the second cathode. The first frequency and the second frequency may be different. Different microwave powers can be output. Compared with the single-cathode microwave source, the multi-cathode microwave source may output alternative microwave powers and/or frequencies by grouping the anode block and a cathode of the multiple cathodes.

In some embodiments, the microwave source may include a specific cathode design in order to prolong a service life of the cathode. For example, a cathode heater may include at least one filament in a double helix configuration (e.g., double helix filament). The at least one filament can be received by a plurality of slots disposed on a cathode support element. A first part of the at least one filament and A second part of the at least one filament may be substantially parallel. When the at least one filament is powered by a power source, directions of respective current flows of the first part and the second part of the at least one filament are inversed, which may reduce the deformation of the filament caused by an attractive force between adjacent coiled segments of a conventional single helix filament. Besides, the use of the slots may facilitate to fix the filament in order to reduce the deformation of the filament. The service life of the filament may be prolonged to some extent.

<FIG> is a schematic diagram illustrating an exemplary radiotherapy system according to some embodiments of the present disclosure. As shown in <FIG>, radiotherapy system <NUM> may include a radiotherapy device <NUM>, a network <NUM>, one or more terminals <NUM>, a processing device <NUM>, and a storage device <NUM>.

The radiotherapy device <NUM> may deliver a radiation beam to a target object (e.g., a patient, or a phantom). In some embodiments, the radiotherapy device <NUM> may include a linear accelerator (also referred to as "linac") <NUM>. The linac <NUM> may generate and emit a radiation beam (e.g., an X-ray beam) from a treatment head <NUM>. The radiation beam may go through one or more collimators (e.g., a primary collimator and/or a multi-leaf collimator (MLC)) of certain shapes, and enter into the target object. In some embodiments, the radiation beam may include electrons, photons, or other types of radiation. In some embodiments, the energy of the radiation beam may be in the megavoltage range (e.g., ><NUM> MeV), and may therefore be referred to as megavoltage beam. The treatment head <NUM> may be coupled to a gantry <NUM>. The gantry <NUM> may rotate, for example, clockwise or counter-clockwise around a gantry rotation axis <NUM>. The treatment head <NUM> may rotate along with the gantry <NUM>. In some embodiments, the radiotherapy device <NUM> may include an imaging element <NUM>. The imaging element <NUM> may receive the radiation beam that passes through the target object, and generate images of patients and/or phantoms before, during and/or after a radiation treatment or a correction process based on received radiation beam. The imaging element <NUM> may include an analog detector, a digital detector, or the like, or a combination thereof. The imaging element <NUM> may be connected to the gantry <NUM> in any connection means, including an extendible housing. Thus, the rotation of the gantry <NUM> may cause the treatment head <NUM> and the imaging element <NUM> to rotate in a coordinated manner. In some embodiments, the radiotherapy device <NUM> may also include a table <NUM>. The table <NUM> may support a patient during a radiation treatment or imaging, and/or support a phantom during a correction process of the radiotherapy device <NUM>. The table <NUM> may be adjustable to suit for different application scenarios.

The network <NUM> may include any suitable network that can facilitate exchange of information and/or data for the radiotherapy system <NUM>. In some embodiments, one or more components of the radiotherapy system <NUM> (e.g., the radiotherapy device <NUM>, the terminal <NUM>, the processing device <NUM>, the storage <NUM>, etc.) may communicate information and/or data with one or more other components of the radiotherapy system <NUM> via the network <NUM>. For example, the processing device <NUM> may obtain plan data from the terminal <NUM> via the network <NUM>. The network <NUM> 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 <NUM> 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, routers, hubs, switches, server computers, and/or any combination thereof. Merely by way of example, the network <NUM> 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 telephone switched network (PSTN), a Bluetooth™ network, a ZigBee™ network, a near field communication (NFC) network, or the like, or any combination thereof. In some embodiments, the network <NUM> may include one or more network access points. For example, the network <NUM> 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 the radiotherapy system <NUM> may be connected to the network <NUM> to exchange data and/or information.

The terminal(s) <NUM> may enable interactions between a user and the radiotherapy system <NUM>. The terminal(s) <NUM> may include a mobile device <NUM>, a tablet computer <NUM>, a laptop computer <NUM>, or the like, or any combination thereof. In some embodiments, the mobile device <NUM> may include a smart home device, a wearable device, a mobile terminal, a virtual reality device, an augmented reality device, or the like, or any combination thereof. In some embodiments, the smart home device may include a smart lighting device, a control device of an intelligent electrical apparatus, a smart monitoring device, a smart television, a smart video camera, an interphone, or the like, or any combination thereof. In some embodiments, the wearable device may include a bracelet, a footgear, eyeglasses, a helmet, a watch, clothing, a backpack, a smart accessory, or 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 computer, a desktop, or the like, or any combination thereof. In some embodiments, the virtual reality device and/or the augmented reality device may include a virtual reality helmet, virtual reality glasses, a virtual reality patch, an augmented reality helmet, augmented reality glasses, an augmented reality patch, or the like, or any combination thereof. For example, the virtual reality device and/or the augmented reality device may include a Google Glass™, an Oculus Rift™, a Hololens™, a Gear VR™, etc. In some embodiments, the terminal(s) <NUM> may be part of the processing device <NUM>.

The processing device <NUM> may process data and/or information obtained from the radiotherapy device <NUM>, the terminal(s) <NUM>, and/or the storage device <NUM>. In some embodiments, the processing device <NUM> may perform one or more radiotherapy operations. For example, the processing device <NUM> may process plan data (e.g., from a treatment planning system (TPS)), and determine motion parameters that may be used to control the motions of multiple components in the radiotherapy device <NUM>. In some embodiments, the processing device <NUM> may be a computer, a user console, a single server or a server group, etc. The server group may be centralized or distributed. In some embodiments, the processing device <NUM> may be local or remote. For example, the processing device <NUM> may access information and/or data stored in the radiotherapy device <NUM>, the terminal <NUM>, and/or the storage device <NUM> via the network <NUM>. As another example, the processing device <NUM> may be directly connected to the radiotherapy device <NUM>, the terminal <NUM>, and/or the storage device <NUM> to access stored information and/or data. In some embodiments, the processing device <NUM> may be implemented on a cloud platform. Merely by way of example, the cloud platform may include a private cloud, a public cloud, a hybrid cloud, a community cloud, a distributed cloud, an inter-cloud, a multi-cloud, or the like, or any combination thereof.

The storage device <NUM> may store data, instructions, and/or any other information. In some embodiments, the storage device <NUM> may store data obtained from the terminal <NUM> and/or the processing device <NUM>. In some embodiments, the storage device <NUM> may store data and/or instructions that the processing device <NUM> may execute or use to perform exemplary methods described in the present disclosure. In some embodiments, the storage device <NUM> may include a mass storage, a removable storage, a volatile read-and-write memory, a read-only memory (ROM), or the like, or any combination thereof. Exemplary mass storage may include a magnetic disk, an optical disk, a solid-state drive, etc. Exemplary removable storage may include a flash drive, a floppy disk, an optical disk, a memory card, a zip disk, a magnetic tape, etc. Exemplary volatile read-and-write memory may include a random-access memory (RAM). Exemplary RAM may include a dynamic RAM (DRAM), a double date rate synchronous dynamic RAM (DDR SDRAM), a static RAM (SRAM), a thyristor RAM (T-RAM), and a zero-capacitor RAM (Z-RAM), etc. Exemplary ROM may include a mask ROM (MROM), a programmable ROM (PROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a compact disk ROM (CD-ROM), and a digital versatile disk ROM, etc. In some embodiments, the storage device <NUM> may be implemented on a cloud platform. Merely by way of example, the cloud platform may include a private cloud, a public cloud, a hybrid cloud, a community cloud, a distributed cloud, an inter-cloud, a multi-cloud, or the like, or any combination thereof.

In some embodiments, the storage device <NUM> may be connected to the network <NUM> to communicate with one or more other components in the radiotherapy system <NUM> (e.g., the processing device <NUM>, the terminal <NUM>, etc.). One or more components in the radiotherapy system <NUM> may access the data or instructions stored in the storage device <NUM> via the network <NUM>. In some embodiments, the storage device <NUM> may be directly connected to or communicate with one or more other components in the radiotherapy system <NUM> (e.g., the processing device <NUM>, the terminal <NUM>, etc.). In some embodiments, the storage device <NUM> may be part of the processing device <NUM>. In some embodiments, the processing device <NUM> may be connected to or communicate with the radiotherapy device <NUM> via the network <NUM>, or at the backend of the processing device <NUM>.

<FIG> is a schematic diagram illustrating exemplary components of a linear accelerator (linac) according to some embodiments of the present disclosure. In some embodiments, linac <NUM> illustrated in <FIG> may be implemented on a radiotherapy device (e.g., the radiotherapy device <NUM>). As illustrated in <FIG>, the linac <NUM> may include a power supply <NUM>, a modulator <NUM>, an electron generator <NUM>, a microwave source <NUM>, an accelerator tube <NUM> and a treatment head <NUM>. In some embodiments, the power supply <NUM> may be configured to provide high voltages (e.g., <NUM> kV) required for proper modulator operation. In some embodiments, the power supply <NUM> may include an alternating current (AC) circuit for supplying the alternating current voltage (ACV). In some embodiments, the power supply <NUM> may include a direct-current (DC) circuit for supplying the direct current voltage (DCV). The modulator <NUM> may be configured to simultaneously provide high voltage pulses (e.g., DC pulses) to the electron generator <NUM> and the microwave source <NUM>. The electron generator <NUM> (e.g., an electron gun, or an electron emitter) may produce electrons injected into the accelerator tube <NUM>. For example, the electron generator <NUM> may produce electrons along a range of angles and emit the electrons along a beam path. The electron beam may be injected into the accelerator tube <NUM>. The electrons in the accelerator tube <NUM> may be accelerated at one or more ranges of kinetic energy using microwaves at one or more ranges of frequency. The accelerated electrons may be transmitted to the treatment head <NUM> for generating a radiation beam. For example, the accelerated electrons may strike a target (e.g., an X-ray target) to generate the radiation beam (e.g., X-ray beam). The radiation beam may go through one or more collimators (e.g., a primary collimator and/or a multi-leaf collimator (MLC)) of certain shapes to form a collimated radiation beam. The collimated radiation beam may irradiate a target object (e.g., a lesion of a subject) to implement radiotherapy.

In some embodiments, the microwave source <NUM> may be configured to generate the microwaves at one or more ranges of frequency. The microwave source <NUM> may be deemed as an oscillator that transforms the DC pulses from the modulator <NUM> into microwave pulses. In some embodiments, the microwave source <NUM> may be a magnetron or a klystron. In some embodiments, the microwave source <NUM> may include a magnetron (also referred to as single-cathode magnetron) composed of one cathode and one anode block. In some embodiments, the microwave source <NUM> may include a magnetron (also referred to as multi-cathode magnetron) composed of multiple cathodes and one anode block. The multiple cathodes may share the same anode block. Through different arrangements of the cathode and the anode block, the microwave sources <NUM> may output different microwave powers.

In some embodiments, the microwave source <NUM> may be a magnetron. In the magnetron, the cathode may be heated by a cathode heater. The cathode heater may include at least one filament. The electrons released from the cathode may be accelerated toward the anode block by the action of pulsed DC electric field. The anode block may include a plurality of resonant cavities. In some embodiments, at least one electromagnet may be disposed surrounding the anode block. A static magnetic field may be applied perpendicular to a cross-section plane of the plurality of resonant cavities. The released electrons can move in complex spirals toward the resonant cavities due to influence of the magnetic field. A resonance effect (or the resonance phenomenon) may occur when the resonant cavities begin to resonate at a certain resonance frequency (e.g., <NUM>). Thus, the resonant cavities may emit microwaves. The microwaves may be transmitted to the accelerator tube <NUM> through a transmission waveguide. The electrons in the accelerator tube <NUM> may be accelerated by the microwave power. More descriptions regarding components of the microwave source may be found elsewhere in the present disclosure (e.g., <FIG>, and the descriptions thereof).

<FIG> illustrates a cross-sectional view of an exemplary microwave source (e.g., a magnetron) according to some embodiments of the present disclosure. As shown in <FIG>, the microwave source <NUM> may include an anode block <NUM> and a cathode <NUM> centered in the anode block <NUM>. The anode block <NUM> and the cathode <NUM> may be coaxial. In some embodiments, the anode block <NUM> may be fabricated into a cylindrical metal block (e.g., a copper block). The anode block <NUM> may include a plurality of resonant cavities <NUM>. For different microwave sources, the number of the resonant cavities may be different. In some embodiments, the number of the resonant cavities may be from <NUM> to <NUM>. Merely for illustration, the anode block <NUM> includes eight resonant cavities <NUM>, that are, eight cylindrical holes around the cathode <NUM>. An interaction space may be formed between the anode block <NUM> and the cathode <NUM>, such as an open space between the anode block <NUM> and the cathode <NUM>. In the interaction space, the electric and magnetic fields interact to exert force upon the electrons. The magnetic field is usually provided by a strong, permanent magnet mounted around the microwave source <NUM> so that the magnetic field is parallel with the axis of the cathode. The electrons released from the cathode <NUM> may travel outwardly in the interactive space. The released electrons can be accelerated toward to the anode block <NUM> by the action of pulsed DC electric field. The electrons may move in complex spirals towards the resonant cavities <NUM> due to the magnetic field. In some embodiments, the resonant cavities <NUM> may exist in various shapes, for example, include but not limited to a semicircular-shape cavity, a circular-shape cavity, a square-shape cavity, a rectangular-shape cavity, a fan-shape cavity, or the like, or any combination thereof.

<FIG> illustrates different forms of an anode block in a microwave source according to some embodiments of the present disclosure. As illustrated in <FIG>, anode block 310a may include a plurality of hole-and-slot type of resonant cavities 312a, anode block 310b may include a plurality of slot-type of resonant cavities 312b, and anode block 310c may include a plurality of vane-type of resonant cavities 312c. The resonant cavities may be usually arranged in a radial fashion.

<FIG> illustrates an exemplary profile of a cathode of a microwave source according to some embodiments of the present disclosure. As illustrated in <FIG>, the cathode <NUM> may include a hollow dumbbell-shape structure. In some embodiments, the cathode <NUM> may be made up of a hollow cylinder of emissive material (e.g., Barium Oxide) surrounding a cathode heater. For example, the cathode <NUM> may include a cathode heater and a thermionic emitter. The cathode heater may include at least one filament. The thermionic emitter may be made up of the hollow cylinder of emissive material. In some embodiments, the cathode heater may be fixed on a cathode support element (e.g., a cathode rod) in a spiral configuration. The cathode support element may be disposed in the hollow space of the thermionic emitter. When the cathode heater is heated by a power source, the outer thermionic emitter may release electrons due to a thermionic emission resulting from the heat radiation. Then the released electrons may travel outwardly in the direction of the anode block. As the electrons nip past the resonant cavities of the anode block, the energy may be passed to the resonant cavities, thus the resonant cavities may resonant at a certain resonant frequency and radiate energy in the form of microwaves.

<FIG> illustrates a cross-sectional view of a cathode of a microwave source according to some embodiments of the present disclosure. As illustrated in <FIG>, the cathode <NUM> may include a cathode support element <NUM>, a cathode heater <NUM> and a thermionic emitter <NUM>.

In some embodiments, a shape of the cathode support element <NUM> may be various, such as a cylinder, a cubic, a cone, and so on. The cross-sectional shape of the cathode support element <NUM> may be formed in a regular shape (e.g., a semicircle, a circle, a square, a triangle, a trapezoid, etc.) or an irregular shape (e.g., an irregular polygon). In some embodiments, the cathode support element <NUM> may be made of an insulative material. Exemplary insulative materials may include plastic, rubber, glass, ceramic, or the like, or any combination thereof. In some embodiments, the insulative cathode support element <NUM> may be formed as one body for reaching a high mechanical strength. The high-strength support element may facilitate to prolong the cathode's service life and guarantee its use reliability.

In some embodiments, the cathode support element <NUM> may include a plurality of slots for receiving the cathode heater <NUM>. In some embodiments, the cathode heater <NUM> may be composed of at least one filament. The at least one filament may be placed in the plurality of slots when wounding around the cathode support element <NUM>. In this way, each coiled segment (or each turn) of the at least one filament may be fixed due to the use of the slots. In some embodiments, the plurality of slots (e.g., slots 602a and 602b illustrated in <FIG>) may be spaced axially around the circumference of the cathode support element <NUM>. In some embodiments, each slot may accommodate a coiled segment when the at least one filament <NUM> wounds around the cathode support element <NUM>. For example, a depth of the slot may be greater than or equal to a diameter of a filament, and a width of the slot may be greater than or equal to the dimeter of the filament. In some embodiments, the width of the slot may refer to a maximum width of the slot (e.g., the width of an opening of the slot).

In some embodiments, the filament may be made of a high-melting-point (e.g., ><NUM>) and conductive material. Exemplary filament materials may include tungsten, molybdenum, rhenium, iridium, or the like, or any combination thereof. In some embodiments, the diameter of the filament may be in the range of <NUM> to <NUM>. In some embodiments, the diameter of the filament may be in the range of <NUM> to <NUM>. In some embodiments, the diameter of the filament may be in the range of <NUM> to <NUM>. In some embodiments, the diameter of the filament may be <NUM>. It should be noted that any suitable filament diameter may be designed and not be limiting in the present disclosure.

<FIG> illustrates two exemplary forms of a filament arrangement according to some embodiments of the present disclosure. As illustrated in <FIG>, filament <NUM> may be arranged into a single helix filament. Two leads of the filament <NUM> may be at the two ends of the filament <NUM>. Coiled segments of the filament <NUM> extend in a one-way direction, for example, from a first lead <NUM> to a second lead <NUM>. In some embodiments, when the filament <NUM> is powered on, a filament current in the filament <NUM> may be the one-way current (for any particular moment), for example, the current flows from the first lead <NUM> to the second lead <NUM>. The direction of filament current in adjacent coiled segments (e.g., adjacent turns) are the same, which results in an interactive attractive force. Adjacent coiled segments may be shrunk due to the attractive force. When the filament <NUM> is powered off, the shrunk coiled segments are restored once the attractive force is disappeared. Since the filament <NUM> is frequently shrunk and restored, such deformation of the filament <NUM> may reduce the service life of the filament <NUM>, and the service life of the cathode.

To resolve the aforementioned issue or similar issue that results in reduced service life, the cathode heater may include at least one filament in a double helix configuration. As illustrated in <FIG>, the filament <NUM> may be a double helix filament. In the structure of the double helix filament, two leads of the filament <NUM>, such as a first lead <NUM> and a second lead <NUM>, may be arranged at same side. In this case, the feeding wires electrically connected to the two leads can be led out from the same side. It is easy that the filament is mounted inside the microwave source lest that redundant feeding wires of the filament leads to a short circuit. A first part (e.g., first continuous coiled segments <NUM> connected to the first lead <NUM>) of the filament <NUM> can spirally extend along a first direction parallel to a filament axis (e.g., axis <NUM> illustrated in a partial enlarged view <NUM>) and in a first helix configuration. A second part (e.g., second continuous coiled segments <NUM> connected to the second lead <NUM>) of the filament <NUM> can spirally extend along a second direction parallel to the filament axis and in a second helix configuration. The first direction and the second direction may be opposite and point to two ends of the filament axis. In some embodiments, the first part (e.g., the first continuous coiled segments <NUM>) and the second part (e.g., the second continuous coiled segments <NUM>) of the filament <NUM> may be operably connected in a loop form illustrated in <NUM>. Coiled segments of the first part and the second part of the filament <NUM> may be interlaced and parallel substantially. In some embodiments, as illustrated in <NUM>, when the filament <NUM> is powered on, directions of respective current flows of the first part and the second part of the filament <NUM> are inversed. Interactive force between the coiled segments may be counteracted due to the inversed currents. Compared with the single helix filament <NUM>, the attractive force between adjacent coiled segments can be avoided, which may reduce the deformation of the filament. In some embodiments, the double helix filament may be composed of a single filament (or a single coil). In some embodiments, the double helix filament <NUM> may be composed of two filaments (or two coils). For example, the first part of the filament <NUM> may include a first filament and the second part of the filament <NUM> may include a second filament. A first end of the first filament can be designated as the first lead <NUM>. A first end of the second filament can be designated of the second lead <NUM>. A second end of the first filament can be electrically connected to a second end of the second filament in the loop form illustrated in <NUM>.

In some embodiments, to reduce the deformation of the filament (e.g., the filament <NUM> or <NUM>), the filament can be spirally wound around a cathode support element having a plurality of slots. <FIG> illustrates a cross-sectional view of a cathode support element (e.g., the cathode support element <NUM> illustrated in <FIG>) according to some embodiments of the present disclosure. As illustrated in <FIG>, a plurality of slots (e.g., first slots 602a and second slots 602b) may be disposed on the cathode support element. The plurality of slots may be spaced axially around the circumference of the cathode support element. In some embodiments, a first portion of the plurality of slots (e.g., the first slots 602a) may be formed through a first continuous spiral groove radially around the circumference of the cathode support element. A second portion of the plurality of slots (e.g., the second slots 602b) may be formed through a second continuous spiral groove radially around the circumference of the cathode support element. The first slots 602a and the second slots 602b are interlaced axially. In some embodiments, a double helix filament (e.g., the filament <NUM> illustrated in <FIG>) may be placed in the plurality of slots so as to fix the filament and reduce the deformation of the filament. For example, the first part of the filament <NUM> may be received by the first slots 602a and the second part of the filament <NUM> may be received by the second slots 602b. In some embodiments, it is required that the size of a slot may be big enough to accommodate a coiled segment of the first part or the second part of the filament <NUM>. For example, a depth of the slot (e.g., a slot 602a or 602b) may be greater than or equal to a diameter (e.g.,<NUM>-<NUM>) of the filament and a width of the slot may be greater than or equal to the dimeter of the filament.

<FIG> illustrates a cross-sectional view of a filament wound around a cathode support element. For example, the double helix filament <NUM> is coiled around the cathode support element <NUM>. The double helix filament <NUM> and the cathode support element <NUM> may be coaxial. Reference numeral <NUM> may represent a circular section of a coiled segment of the first part of the filament <NUM>, and reference numeral <NUM> may represent a circular section of a coiled segmented of the second part of the filament <NUM>.

<FIG> illustrates a cross-sectional view of an exemplary microwave source according to some embodiments of the present disclosure. Merely for illustration, microwave source <NUM> illustrated in <FIG> may be a magnetron. The magnetron may be a tunable magnetron. The microwave source <NUM> may include an anode block <NUM>, a cathode <NUM> centered in the anode block <NUM>, a tuning element <NUM>, a microwave transmitter <NUM> and a transmission waveguide <NUM>. As described in connection with <FIG>, the anode block <NUM> may include a plurality of resonant cavities 802a. The resonant cavities 802a may exist in the form of the hole-and-slot type illustrated in <FIG>. The cathode <NUM> may be removably positioned in the center of the anode block. As described in connection with <FIG>, the cathode <NUM> may include a cathode heater, a thermionic emitter surrounding the cathode heater, and a cathode support element. The cathode heater may include a double helix filament. The double helix filament can spirally wound around the cathode support element and received by a plurality of slots on the cathode support element. More descriptions regarding the anode block and the cathode may be found elsewhere in the present disclosure (e.g., <FIG>, and the descriptions thereof), and not repeated.

The tuning element <NUM> may be configured to adjust a resonant frequency of the microwave source <NUM>. The resonant frequency may be changed by varying the inductance or capacitance of the resonant cavities of the microwave source. In some embodiments, the tuning element <NUM> may be inserted into the hole portion of the hole-and-slot cavities. The tuning element <NUM> may change the capacitance of the resonant cavities by altering the ratio of surface areas to cavity volume in a high-current region. The resonant frequency of the microwave source <NUM> may be adjusted higher or lower through an insertion or removement of the tuning element <NUM>. For example, when the tuning element <NUM> is inserted into the anode hole, the capacitance of the cavity can be increased, thereby the resonant frequency may be decreased. In some embodiments, the microwave source <NUM> may include multiple tuning elements <NUM> operably connected to each resonant cavity 802a. Merely for illustrative purposes, just one tuning element <NUM> is illustrated. In some embodiments, the tuning element <NUM> may be made of an electrically conductive material (e.g., copper, aluminum, or other metal materials).

The microwave transmitter <NUM> may be configured to transmit the microwaves generated by the microwave source <NUM>. The microwaves may be transmitted into the transmission waveguide <NUM> (e.g., the transmission waveguide illustrated in <FIG>). Then transmission waveguide <NUM> may transmit the microwaves to an accelerator tube (e.g., the accelerator tube <NUM>) in order to provide the kinetic energy to accelerate electrons in the accelerator tube.

<FIG> illustrates a cross-sectional view of an exemplary microwave source according to some embodiments of the present disclosure. As illustrated in <FIG>, microwave source <NUM> may be a multi-cathode microwave source (e.g., a multi-cathode magnetron). The microwave source <NUM> may include an anode block <NUM> and multiple cathodes, such as a first cathode <NUM> and a second cathode <NUM>. In some embodiments, the multiple cathodes may be removably positioned in the center of the anode block <NUM>. For example, as illustrated in <FIG>, a first cathode <NUM> is positioned in the center of anode block <NUM>. As illustrated in <FIG>, second cathode <NUM> is positioned in the center of anode block <NUM>. In some embodiments, when an individual cathode (e.g., the first cathode <NUM> or the second cathode <NUM>) of the multiple cathodes is removably positioned in the center of the anode block, microwaves having a specific frequency (e.g., a specific microwave power) are generated in response to an occurrence of a resonance effect caused by the anode block and the cathode. More descriptions regarding the anode block and the cathode may be found elsewhere in the present disclosure (e.g., <FIG>, and the descriptions thereof), and not be repeated.

In some embodiments, respective diameters of the multiple cathodes may be different. In some embodiments, the diameters of at least two of the multiple cathodes may be different. For example, the first cathode diameter may be <NUM> and the second cathode diameter may be <NUM>. In some embodiments, the microwave source <NUM> may include a connector <NUM>. The multiple cathodes may be mechanically connected to each other by the connector <NUM>. The connector <NUM> (e.g., a support rod) may be configured to support and connect each cathode. In some embodiments, the cathode support element (e.g., the cathode support element <NUM>) may be a portion of the connector <NUM>. The connector <NUM> may be made of an insulative material. In some embodiments, the microwave source <NUM> may include a limiting member <NUM>. An end of the connector <NUM> may be operably connected to the limiting member <NUM>. In some embodiments, the microwave source <NUM> may include a guide slot <NUM>. The limiting member <NUM> may be disposed in the guide slot <NUM>. In some embodiments, the limiting member <NUM> may move (e.g., slide) along the guide slot <NUM> in order to position the cathode of the multiple cathodes. For example, when the limiting member <NUM> is moved to a first location, the first cathode <NUM> can be positioned in the center of the anode block <NUM>. When the limiting member <NUM> is moved to a second location, the second cathode <NUM> can be positioned in the center of the anode block <NUM> and the first anode cathode <NUM> may be moved out. In some embodiments, the limiting member <NUM> may be driven by various driving devices. Exemplary driving devices may include a hydraulic driver, a pneumatic driver, an electric actuator. In some embodiments, the various driving devices may not cause interferences for the generation of microwaves.

An electronic efficiency of the microwave source (e.g., the magnetron) may rely on a ratio of diameters of the cathode and the anode block (also referred to as "diameter ratio"). When the dimeter ratio is in a specific range, the electron efficiency may be at an optimal value, and an output power of the microwave source may be maximum. For example, for an eight-cavities anode block, when the diameter ratio is in the rage of <NUM>-<NUM>, the electronic efficiency of the magnetron may be optimal. As another example, for a twelve-cavities anode block, when the diameter ratio is in the range of <NUM>-<NUM>, the electronic efficiency of the magnetron may be optimal. As a further example, for a sixteen-cavities anode block, when the diameter ratio is in the range of <NUM>-<NUM>, the electronic efficiency of the magnetron may be optimal.

In some embodiments, the output power of the microwave source can be changed by varying the diameter ratio of the anode block to the cathode. In some embodiments, for a specific anode block, the diameter ratio can be changed by alternating the cathodes having different diameters. Merely for illustration, for a magnetron including a twelve-cavities anode block, its resonant frequency is <NUM> and maximum output power is <NUM> MW. Given that the diameter of the anode block is <NUM>. The maximum output power of the magnetron can be reached only if the diameter of the cathode in the range of <NUM>-<NUM>. It is understood that, when the diameter of a cathode is less than <NUM> or greater than <NUM>, the magnetron may output a relatively small microwave power. By arranging the constant anode block and one of the cathodes having different diameters, the magnetron may output alternative microwave powers. The alternative microwave powers may be used to generate radiation beams of different energies. For example, the diameter of the anode block <NUM> is set as <NUM> and the diameter of the first cathode <NUM> is set as <NUM>. When the anode block <NUM> and the first cathode <NUM> are powered on, the microwave source <NUM> may output the maximum microwave power for accelerating electrons in the accelerator tube <NUM> to generate therapeutic radiation beams. The therapeutic radiation beams may be applied to the target object for eliminating tumor tissues. As another example, the diameter of the second cathode <NUM> is set as <NUM>. When the anode block <NUM> and the second cathode <NUM> are powered on, the microwave source <NUM> may output a relatively small microwave power for accelerating electrons in the accelerator tube <NUM> to generate imaging radiation beams. For the IGRT device, the imaging radiation beams may be used to image a region of interest (ROI) related to the target object. The radiotherapy procedure may be guided according to the ROI related information (e.g., a tumor region).

In some embodiments, the resonant frequency of the microwave source can be changed by alternating different cathodes. The resonant frequency of the microwave source may rely on an equivalent capacitance and inductance of the microwave source. For example, the resonant frequency, <MAT>, where L denotes the inductance and C denotes the equivalent capacitance. For the constant anode block, the larger the diameter of the cathode, the smaller the distance between the cathode and the anode block, thereby the equivalent capacitance becomes larger. The resonant frequency may be changed with the equivalent capacitance. In some embodiments, by switching cathodes of different diameters, different resonant frequency may be produced accordingly. In addition, the tuning element (e.g., the tuning element <NUM>) of the microwave source may slightly adjust the resonant frequency, such as ±<NUM>. The adjustable range of the resonant frequency of the microwave source may be enlarged due to the use of the multiple cathodes and the tuning element. It is understood that the frequencies of output microwaves may be changed varying with the characteristics (e.g., resonant frequencies) of the microwave source. Specific microwave frequency may be produced when different cathodes are applied.

Having thus described the basic concepts, it may be rather apparent to those skilled in the art after reading this detailed disclosure that the foregoing detailed disclosure is intended to be presented by way of example only and is not limiting. Various alterations, improvements, and modifications may occur and are intended to those skilled in the art, though not expressly stated herein. These alterations, improvements, and modifications are intended to be suggested by this disclosure, and are within the scope of the exemplary embodiments of this disclosure.

" Furthermore, aspects of the present disclosure may take the form of a computer program product embodied in one or more computer-readable media having computer readable program code embodied thereon.

Such a propagated signal may take any of a variety of forms, including electromagnetic, optical, or the like, or any suitable combination thereof.

Computer program code for carrying out operations for aspects of the present disclosure may be written in any combination of one or more programming languages, including an object-oriented programming language such as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C++, C#, VB. NET, Python or the like, conventional procedural programming languages, such as the "C" programming language, Visual Basic, Fortran <NUM>, Perl, COBOL <NUM>, PHP, ABAP, dynamic programming languages such as Python, Ruby, and Groovy, or other programming languages.

Furthermore, the recited order of processing elements or sequences, or the use of numbers, letters, or other designations, therefore, is not intended to limit the claimed processes and methods to any order except as may be specified in the claims. Although the above disclosure discusses through various examples what is currently considered to be a variety of useful embodiments of the disclosure, 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 modifications and equivalent arrangements that are within the scope of the disclosed embodiments. For example, although the implementation of various components described above may be embodied in a hardware device, it may also be implemented as a software-only solution, for example, an installation on an existing server or mobile device.

Similarly, it should be appreciated that in the foregoing description of embodiments of the present disclosure, 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 of the various inventive embodiments. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed subject matter requires more features than are expressly recited in each claim. Rather, inventive embodiments lie in less than all features of a single foregoing disclosed embodiment.

In some embodiments, the numbers expressing quantities or properties used to describe and claim certain embodiments of the application are to be understood as being modified in some instances by the term "about," "approximate," or "substantially. " For example, "about," "approximate," or "substantially" may indicate ±<NUM>% variation of the value it describes, unless otherwise stated. Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the application are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable.

Claim 1:
A microwave source (<NUM>, <NUM>, <NUM>, <NUM>), comprising:
an anode block (<NUM>, <NUM>, <NUM>); and
multiple cathodes (<NUM>, <NUM>, <NUM>, <NUM>), at least two diameters of at least two cathodes (<NUM>, <NUM>) of the multiple cathodes (<NUM>, <NUM>, <NUM>, <NUM>) being different, and each of the multiple cathodes (<NUM>, <NUM>, <NUM>, <NUM>) comprising:
a cathode support element (<NUM>) having a plurality of slots, the plurality of slots being axially around a circumference of the cathode support element (<NUM>); and
a cathode heater (<NUM>) including at least one filament (<NUM>),
wherein a first part (<NUM>) of the at least one filament (<NUM>) is wound around the cathode support element (<NUM>) along a first direction and received by a first portion of the plurality of slots, and a second part (<NUM>) of the at least one filament (<NUM>) is wound around the cathode support element (<NUM>) along a second direction and received by a second portion of the plurality of slots;
a connector (<NUM>), the multiple cathodes (<NUM>, <NUM>, <NUM>, <NUM>) being mechanically connected to each other by the connector (<NUM>);
a limiting member (<NUM>), an end of the connector (<NUM>) being operably connected to the limiting member (<NUM>);
a guide slot (<NUM>), the limiting member (<NUM>) being disposed in the guide slot and configured to move along the guide slot (<NUM>) to position a cathode of the multiple cathodes (<NUM>, <NUM>, <NUM>, <NUM>) in a center of the anode block (<NUM>, <NUM>, <NUM>);
wherein at least two microwaves having different frequencies are generated in response to an occurrence of a resonance effect caused by the at least two cathodes (<NUM>, <NUM>) respectively and the anode block (<NUM>, <NUM>, <NUM>).