High dose rate radiation therapy system and target

Abstract

The invention relates to a high dose rate radiation therapy system and a target. A radiation system includes an X-ray target configured to convert an electron beam into an X-ray beam. The X-ray target includes a plurality of target layers, and each of the plurality of target layers is configured to convert a portion of the electron beam into a portion of the X-ray beam.

Description

Technical Field

[0001] One or more example embodiments relate to a target and / or a radiation therapy system including the target. Background Art

[0002] External beam radiation therapy can be used in the treatment of various cancers and non-malignant conditions. Typically, ionizing radiation (including, for example, photons, such as X-rays, gamma rays, and charged particles (such as protons and electrons)) is directed at the region of interest. In many cases, this ionizing radiation is generated by a linear accelerator or a cyclotron.

[0003] Ultra-high dose rate (UHDR) radiotherapy is an emerging radiotherapy regimen that appears to reduce radiation-induced toxicity while maintaining similar tumor responses to more conventional radiotherapy regimens - known as the FLASH effect. UHDR radiotherapy can be characterized as delivering a high radiation rate, e.g., greater than about 40 Gray (Gy) per second, which allows the total radiotherapy treatment dose, or a large portion of the total radiation dose, to be delivered in a fraction of a second, whereas conventional radiotherapy requires several minutes. For example, a conventional radiotherapy treatment may include a total dose of 12 Gray (Gy) to 25 Gray delivered at a rate of up to 0.4 Gy / s, which requires several minutes of treatment time. In contrast, UHDR radiotherapy can deliver a similar total dose at a rate of 40 Gy / s, which requires a fraction of a second of treatment time.

[0004] However, generating such high doses of radiotherapy requires increasing the instantaneous dose rate by several orders of magnitude compared to conventional instantaneous dose rates. For example, the instantaneous dose rate of UHDR radiotherapy can be more than 100 times higher than the instantaneous dose rate used in conventional radiotherapy. For FLASH photon (X-ray) radiotherapy, this uses a corresponding increase in the electron current that strikes the X-ray target. Summary of the invention

[0005] The scope of protection sought by various example embodiments is defined by the independent claims. Example embodiments and / or features described in this specification that do not fall within the scope of the independent claims (if any) should be interpreted as examples that aid in understanding the various embodiments.

[0006] Unfortunately, conventional X-ray targets and associated components are not suitable for the high currents and / or instantaneous dose rates characteristic of UHDR radiotherapy. For example, conventional X-ray targets may degrade and / or be destroyed if exposed to the high beam currents and / or instantaneous dose rates characteristic of UHDR radiotherapy.

[0007] According to at least one example embodiment, a radiation system includes an X-ray target configured to convert an electron beam into an X-ray beam. The X-ray target includes a plurality of target layers, and each of the plurality of target layers is configured to convert a portion of the electron beam into a portion of the X-ray beam. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Example embodiments will be more fully understood from the detailed description and accompanying drawings given below herein, wherein like elements are denoted by like reference numerals, which are given by way of illustration only and thus do not limit the present disclosure.

[0009] Figure 1 A block diagram of a radiation processing system according to an example embodiment is illustrated.

[0010] Figure 2 FIG. 1 illustrates an exemplary embodiment of the present invention. Figure 1 A side cross-sectional schematic diagram of an exemplary beam path in a radiation treatment system.

[0011] Figure 3A A side view of an X-ray target is illustrated according to one or more example embodiments.

[0012] Figure 3B A top view of an X-ray target according to one or more example embodiments is illustrated.

[0013] Figure 4 A side view of an X-ray target and a heat transfer material according to one or more example embodiments is illustrated.

[0014] Figure 5A-5C A target assembly according to one or more example embodiments is illustrated.

[0015] Figure 6 A block diagram of a control system is illustrated, which may be utilized to implement an embodiment.

[0016] It should be noted that these figures are intended to illustrate the general characteristics of methods, structures and / or materials utilized in certain example embodiments and are intended to supplement the written description provided below. However, these figures are not drawn to scale and may not accurately reflect the precise structure or performance characteristics of any given embodiment, and should not be interpreted as defining or limiting the range of values ​​or properties covered by the example embodiments. The use of similar or identical reference numerals in the various figures is intended to indicate the presence of similar or identical elements or features. DETAILED DESCRIPTION

[0017] Various example embodiments will now be described more fully with reference to the accompanying drawings, in which some example embodiments are shown.

[0018] Detailed illustrative embodiments are disclosed herein. However, the specific structural and functional details disclosed herein are only for representative purposes of describing example embodiments. However, example embodiments may be embodied in many alternative forms and should not be construed as being limited to the embodiments set forth herein.

[0019] It should be understood that there is no intention to limit the example embodiments to the specific forms disclosed. On the contrary, the example embodiments should cover all modifications, equivalents and alternatives that fall within the scope of the present disclosure. Throughout the description of the drawings, the same reference numerals refer to the same elements.

[0020] As discussed herein, the terms "one or more" and "at least one" may be used interchangeably.

[0021] It should be understood that various example embodiments may be used in combination.

[0022] Although one or more example embodiments may be discussed herein with respect to an embodiment of an X-ray target positioned in a treatment head of a radiation therapy system, it should be understood that the example embodiments should not be limited to such an example. Rather, the described X-ray target may also be deployed as an attachment to a treatment head.

[0023] Figure 1 A block diagram of a radiation processing system according to an example embodiment is illustrated.

[0024] Figure 1 A block diagram of an exemplary radiation treatment system 100 is shown, which may be used as a platform for the example embodiments. The radiation treatment system 100 may be similar to Radiation therapy systems, commercially available from Varian Medical Systems of Palo Alto, California.

[0025] The stand 10 supports a rotatable gantry 20 with a treatment head 30. The treatment head 30 may extend into the gantry 20. A control unit 18 is arranged near the stand 10 and comprises control circuitry for controlling different operating modes of the system 100.

[0026] The radiation treatment system 100 includes a linear accelerator 40, for example, located in the gantry 20, for generating radiation beams. Typically, the radiation treatment system 100 can generate electron (particle) beams or X-ray (photon) beams for performing radiation therapy treatment on a patient on a treatment bed 35. Other radiation treatment systems can generate light ion particles, such as protons, alpha particles, or carbon ions. For ease of the following disclosure, only X-ray (photon) radiation will be discussed.

[0027] A high voltage source is provided in the support and / or in the gantry to provide voltage to an electron gun (not shown) positioned on an accelerator rail located in the gantry 20. Electrons are emitted from the electron gun into the accelerator 40, where they are accelerated. The source provides radio frequency (microwave) power to generate an electric field in the waveguide. The electrons emitted from the electron gun are accelerated by the electric field in the waveguide and leave the waveguide as a high energy electron beam 45 (e.g., megavolt energy). In some embodiments, the electron beam 45 can pass through a set of curved plane scanning magnets 47. In some embodiments, the electron beam 45 can pass through a set of curved magnets 49 to redirect the electron beam 45 from substantially horizontal to substantially vertical. The electron beam 45 then enters a drift tube 52 and strikes an appropriate X-ray target 50 (e.g., a bremsstrahlung transmission target), thereby converting a portion of the electron beam 45 into X-rays (photons) 55 in the direction of the patient P. The drift tube 52 reduces scattering before striking the target 50 and effectively reduces the source-to-surface distance (SSD) between the treatment surface and the target 50. The SSD may be measured from the top of the target 50 , the middle of the target 50 , the bottom of the target 50 , or any other location in the target 50 .

[0028] like Figure 1 , the patient P is shown lying on the treatment bed 35. High-energy photons as described above are emitted from the treatment head 30 in a divergent beam 104. Typically, the patient plane 116 is positioned, for example, about one meter from the X-ray source, and the axis of rotation of the gantry 20 is located on the patient plane 116 so that the distance between the target 50 and the isocenter 178 remains constant when the gantry 20 rotates. It should be understood that for photon FLASH treatment, the patient plane 116 can be less than one meter from the electron source. The isocenter 178 is at the intersection of the axis of rotation of the gantry 20 and the central axis of the beam 122. The treatment volume to be irradiated can be located near the isocenter 178, or in some embodiments can be located closer to or farther away from the treatment head 30. It should be understood that some treatment plans can utilize a primary treatment target that is offset from the central beam axis, and such an arrangement is within the scope of the example embodiments.

[0029] Figure 2 A side schematic diagram of an exemplary beam path 200 within a radiation treatment system 100 according to an example embodiment is illustrated. It should be understood that the illustrated components of the beam path 200 are exemplary and that not all components may be required in some embodiments. Additional components, such as a flattening filter (not shown), may also be included according to embodiments of the present invention. In some embodiments, the electron beam 45 may pass through a set of cross-plane scanning magnets 201 before striking the x-ray target 50. As previously described, the electron beam 45 strikes the x-ray target 50, generating an x-ray radiation beam 210.

[0030] Radiation beam 210 passes through monitoring chamber 250, sometimes referred to or indicated as an "ion chamber". Monitoring chamber 250 is used to measure radiation therapy dose. X and Y jaws 260 and the leaves of multi-leaf collimator (MLC) 270 are used to shape radiation beam 210 into a desired shape and / or beam profile for patient treatment.

[0031] In some embodiments, the primary collimator 220 may include a plurality of selectable collimators and / or filters. The primary collimator 220 typically includes an X-ray blocking material and may be positioned on the head 30 ( Figure 1 ) to define the width of the X-ray beam at the patient plane. Typically, the X and Y jaws 260 are movable and, when fully opened, define the patient plane 116 ( Figure 1 ) at the maximum beam width at the X-ray beam. The MLC 270 may be positioned at the exit of the head 30 to further shape the X-ray beam. An exemplary MLC may use up to 120 individually controllable blades (e.g., thin sheets of tungsten) that may be moved in or out of the X-ray beam under control of the system software.

[0032] When a high energy electron beam (e.g., 22 MeV) passes through an X-ray target (e.g., tungsten (W) or tantalum (Ta)), the linear energy transfer (LET) determines the heat generation profile within the target. LET refers to the energy transferred to the material per unit distance of the ionized particles. As the electron beam penetrates deeper into the target material, the LET gradually increases, reaching a maximum value at a critical thickness. Beyond this critical thickness, the stopping power becomes too high, resulting in rapid absorption of the beam energy. For example, for 22 MeV, the critical thickness of W / Ta is about 1.15 mm.

[0033] The X-ray target 50 is designed to include multiple thin layers of spatially separated targets, which ensures that (i) the thickness of each target layer is much less than a critical thickness, and ii) 99% of incident electrons lose all of their energy (are absorbed) in the X-ray target 50 .

[0034] According to an example embodiment, the X-ray target 50 is configured to operate in UHDR radiation therapy and absorbs >99% of incident electrons. According to other example embodiments, the X-ray target 50 is also configured to operate in ultra-high dose rate (UHDR) radiation therapy, such as at least 1 Gray (Gy) per second, and absorbs >99% of incident electrons.

[0035] Figure 3A A side view of an X-ray target is illustrated according to one or more example embodiments.

[0036] like Figure 3AAs shown in FIG. 4 , the X-ray target 50 includes a plurality of target layers 350 - 1 to 350 - n . Each of the plurality of target layers 350 - 1 to 350 - n is configured to convert a portion of the electron beam 45 into a portion of the radiation beam 210 .

[0037] In some example embodiments, the plurality of target layers 350-1 to 350-n are stacked in series, for example, along the central axis of the beam 122. However, example embodiments are not limited thereto. In addition, the plurality of target layers 350-1 to 350-n may be spaced apart by the same distance or by different distances. For example, a first distance between target layer 350-1 and target layer 350-2 may be different from a second distance between target layer 350-2 and target layer 350-3.

[0038] The target layers 350-1 to 350-n may have the same thickness or different thicknesses. Each of the target layers 350-1 to 350-n is relatively thin and includes a refractory metal. Refractory metals are characterized as high-Z materials, for example, materials including elements having high atomic numbers ("Z") of protons in the nucleus and having high melting temperatures. As used herein, "high Z" refers to or describes elements having atomic numbers of 42 (corresponding to molybdenum (Mo)) or greater. Exemplary elements include tungsten (W), tantalum (Ta), molybdenum (Mo), gold (Au) and / or antimony (Sb). The total thickness of the target layers 350-1 to 350-n is selected to be sufficient to generate a desired dose of X-rays while minimizing attenuation and energy loss of incident high-energy electrons.

[0039] In some example embodiments, for an X-ray target 50 including tantalum (Ta) or tungsten (W), each of the target layers 350-1 to 350-n is 0.1 mm. In some example embodiments, each of the target layers 350-1 to 350-n may be the same material.

[0040] In some example embodiments, the total thickness of the target layers 350-1 to 350-n may be the same as the thickness of a monolithic target, such as 6.5 mm for an X-ray target 50 including Ta. In some example embodiments, each of the target layers 350-1 to 350-n includes Ta, and each of the target layers 350-1 to 350-n may be a Ta foil.

[0041] For example, an exemplary UHDR radiotherapy treatment may require electron energies of at least 50 MeV, yielding average beam powers of up to 25 kW.

[0042] Since the decay of high energy electrons within the X-ray target 50 generates heat, separating the X-ray target 50 into multiple layers separates the electrons between the target layers 350-1 to 350-n, and the spacing between the target layers 350-1 to 350-n absorbs heat from the X-ray target 50, which must be withstood and / or removed from the X-ray target 50. Reducing the heating of the X-ray target 50 improves the stability and reliability of the UHDR radiotherapy system.

[0043] In some example embodiments, while the total thickness of the target layers 350-1 to 350-n can be the same as the thickness of a monolithic target, the spacing of the target layers 350-1 to 350-n in series along the electron beam path allows for thermal management via at least one of a heat sink, air cooling, radiation transfer, or (high pressure) water cooling. For example, the target 50 can be used with the cooling system described in U.S. Patent No. 8,761,347, the entire contents of which are incorporated herein by reference. The spacing of the target layers 350-1 to 350-n can be paired with existing thermal management solutions involving moving targets or scanning beams, such as the thermal management solutions described in U.S. Application No. 17 / 709,060, the entire contents of which are incorporated herein by reference. In addition, by keeping the total thickness of the target layers 350-1 to 350-n the same as a monolithic target, the electrons are stopped within the target, eliminating the need for additional electron contamination management. Furthermore, by keeping the total thickness of the target layers 350 - 1 to 350 - n the same as a monolithic target, no additional requirements are placed on scanning control of the electron beam, nor is there any need to manage rotating (or otherwise moving) the target.

[0044] In an example embodiment, target layers may be added or removed based on the energy level of beam 45 .

[0045] Figure 3B FIG. 2 illustrates a top view of an X-ray target according to one or more example embodiments. Figure 3B As shown in FIG. 5 , the X-ray target 50 (and each of the target layers 350 - 1 to 350 - n) is circular. The size of the target layer (e.g., the area of ​​the top surface) is larger than the incident beam spot size to maximize the bremsstrahlung efficiency and avoid incident electrons passing through without any interaction. Figure 3A-3B As shown in the exemplary embodiment of , the diameters of the plurality of target layers 350-1 to 350-n respectively follow the divergence of the beam spot size. More specifically, the first target layer 350-1 struck by the electron beam 45 has the smallest diameter among the target layers 350-1 to 350-n. The last target layer 350-n has the largest diameter among the target layers 350-1 to 350-n, and each of the remaining target layers 350-2 to 350-n-1 has a diameter that is larger than the previous target layer (in the direction of the electron beam 45) and smaller than the subsequent target layer (in the direction of the electron beam 45).

[0046] Although Figure 3A-3B The target layers 350 - 1 to 350 - n are illustrated as being circular, but it should be understood that the target layers 350 - 1 to 350 - n may be another shape, such as a triangle or a rectangle.

[0047] Figure 4 A side view of an X-ray target and a heat transfer material according to one or more example embodiments is shown. Figure 4 As shown in FIG. 4 , the heat transfer material layers 410 - 1 to 410 - n are respectively disposed on the plurality of target layers 350 - 1 to 350 - n. Figure 4 In the example shown in , n layers of heat transfer material layers 410 are located in target 50. Heat transfer material layers 410-1 to 410-n may be attached to target layers 350-1 to 350-n, respectively, using thermally conductive paste or any other known means.

[0048] The thickness of the target layer 350 and the heat transfer layer 410 are not drawn to scale. In some example embodiments, all the heat transfer layers are thicker than the target layer, in other example embodiments, all the target layers are thicker than the heat transfer layers, and in other example embodiments, some of the heat transfer layers are thicker than the target layer. In other example embodiments, the target layer and the heat transfer layer may have the same thickness.

[0049] The heat transfer material layers 410-1 to 410-n transfer and absorb heat from the plurality of target layers 350-1 to 350-n to reduce heating of the X-ray target 50. The heat transfer material layers 410-1 to 410-n may be copper or any other known material with high thermal conductivity, such as diamond. Each of the heat transfer material layers 410-1 to 410-n may have a thermal conductivity of at least 400 W / (mK). In some example embodiments, the shape of each heat transfer material layer 410-1 to 410-n is such that it covers the top surface of the corresponding target layer 350-1 to 350-n. As an example, when the target layer 350-1 is cylindrical / circular, the heat transfer material layer 410-1 has the same diameter as the target layer 350-1. The thickness of each heat transfer material layer 410-1 to 410-n may be determined by the desired energy absorbed by the heat transfer material layer. In some example embodiments, the heat transfer material layer 410-1 may have a greater thickness than the other heat transfer material layers 410-2 to 410-n. The thickness of each heat transfer material layer may be sufficient to dissipate heat into the water channels in the same layer of the target.

[0050] Figure 5A5 is a perspective view of an exemplary target assembly 500 according to some example embodiments. The target assembly 500 positions a target in a beam path in a photon mode to generate X-rays, or moves the target out of the beam path in an electron mode. The target assembly 500 includes a channel support 502, a substrate 504 supporting one or more target buttons 506, and a cooling tube 508 coupled to the substrate 504 to provide a cooling fluid. At least one of the one or more target buttons 506 can be a target 50. A channel can be provided in the substrate 504 adjacent to or around the target button 506 for circulating a cooling fluid to dissipate heat generated during target operation. The substrate 504 and the cooling tube 508 can be supported by a support assembly 510 that is movable relative to the channel support 502.

[0051] Target assembly 500 and cooling tube 508 are further described in US Pat. No. 8,761,347, the entire contents of which are incorporated herein by reference.

[0052] Thus, target 50 may be used with existing cooling mechanisms.

[0053] Figure 5B-Figure 5C At least one example embodiment using a plurality of cooling tubes is illustrated. Figure 5B 5 shows a cross-sectional view of the target assembly 500. In some example embodiments, a plurality of cooling tubes 508-1 to 508-n may be used for the target layers 350-1 to 350-n, respectively. Figure 5B-Figure 5C as shown in .

[0054] like Figure 5B As shown in FIG. 1 , each of the target layers 350-1 to 350-n is placed in a corresponding heat dissipation layer 504-1 to 504-n. More specifically, each heat dissipation layer 504-1 to 504-n has a receiving area 520 having a diameter that is the same as or slightly larger than that of the target layer 350 corresponding to the heat dissipation layer 504-1 to 504-n. Figure 5B Although not shown in the figure, the heat transfer material layers 410-1 to 410-n may also be placed on the target layers 350-1 to 350-n, respectively. In some example embodiments, only a selected number of heat transfer material layers may be used. For example, only the heat transfer material layer 410-1 may be used, and the remaining target layers 350-2 to 350-n may not have corresponding heat transfer material layers.

[0055] Each of the layers 1 to n includes a cooling pipe 508 .

[0056] The target assembly 500 may include multiple slots to accommodate different numbers of target layers. For example, the target assembly may have n slots and n cooling tubes. Based on the energy level of the beam 45, a selected number of target and heat sink layers may be inserted into the n slots. The selected number may be n or less than n. Each of the slots may have a defined mount for a target and heat sink layer. Furthermore, while the combination of layers is described as a target and heat sink layer, it should be understood that the slots may accommodate a combination of a target layer and a heat transfer material layer, and / or a combination of a target layer, a heat transfer material layer, and a heat sink layer.

[0057] As an example, the target assembly 500 may include five or six slots to accommodate a 22 meV beam, where each target layer is a 1 mm thick layer and each heat transfer material layer is 2 mm thick.

[0058] Figure 5C A top view (eg, beam viewing angle) of the first layer is shown. The remaining layers are identical except for the size of the target layer within the corresponding layer.

[0059] like Figure 5C As shown in , the cooling pipe 508-1 provides water (or another coolant) to the cooling channel 550 through the coupling 530. The cooling channel 550 and the coupling 530 may be embedded in the heat sink layer 504-1. The cooling channel 550 may have a general U-shape. The curved portion 555 of the U-shaped cooling channel 550 may have a curvature that matches the curvature of the target layer 350-1. However, example embodiments are not limited thereto, and the cooling channel 550 may have different shapes.

[0060] In addition, each of the couplings 530 may include a valve that is operable based on whether a target and a heat sink are being used in the tank. For example, if a target and a heat sink are present in the tank, the valve opens to allow water to flow through the channel in the heat sink. If a target and a heat sink are not present in the tank, the corresponding valve closes.

[0061] Return to reference Figure 5A , the target assembly 500 may be moved by a linear shaft 514, which includes a motor 514a, a ball screw, a coupler 514b coupling the motor and the ball screw, and a ball screw 514c engaged with the ball screw.

[0062] The target assembly 500 may include one or more targets, each optimized to match the energy of the incident electron beam. For example, the target assembly 500 may include a first target 506a for a first photon mode, a second target 506b for a second photon mode, and a third target 506c for a third photon mode. It should be noted that a different number of targets may be included in the target assembly 500. In operation, the linear axis 514 moves or positions one of the targets 506 in the beam path of the photon mode. In the electron mode, the linear axis 514 moves the target 506 out of the beam path to allow the electron beam to pass unimpeded.

[0063] It should be noted that a different number of targets may be included in target assembly 500. In operation, for photon mode, linear axis 514 moves or positions one of targets 506 in the beam path. In electron mode, linear axis 514 moves target 506 out of the beam path to allow the electron beam to pass unimpeded.

[0064] Figure 6 A block diagram of a control system is illustrated, which may be utilized to implement an embodiment.

[0065] In some embodiments, Figure 6 The control system 600 shown in FIG. 1 may be used to implement the control unit 18. The control system 600 may also be an example of any control system described herein.

[0066] The control system 600 includes a bus 602 or other communication mechanism for transmitting information, and a processing circuit device 604 (e.g., at least one processor and / or ASIC) coupled to the bus 602 to process information. In examples where the processing circuit device 604 is hardware (e.g., a processor) configured to execute stored instructions, the control system 600 also includes a main memory 606, such as a random access memory (RAM) or other dynamic storage device, coupled to the bus 602 for storing information and instructions executed by the processing circuit device 604. The main memory 106 can also be used to store temporary variables or other intermediate information during the execution of instructions to be executed by the processing circuit device 604. The control system 600 also includes a read-only memory (ROM) 608 or other static storage device, which is coupled to the bus 602 for storing static information and instructions for the processing circuit device 604. A data storage device 610 (such as a magnetic disk or optical disk) may be provided and coupled to the bus 602 for storing information and instructions.

[0067] Control system 600 may be coupled to a display 612 (such as a tablet) via bus 602 for displaying information to a user. An input / output device 614 (such as a touch screen) is coupled to bus 602 for transmitting information and command selections to processing circuitry 604. Another type of user input device is a cursor control 616, such as a mouse, trackball, or cursor direction keys, for transmitting direction information and command selections to processing circuitry 604 and for controlling cursor movement on display 612. The input device typically has two degrees of freedom in two axes, a first axis (e.g., x) and a second axis (e.g., y), which allows the device to specify a position in a plane.

[0068] Although the display 612 and I / O devices 614 are shown as being external to the control system 600, it is understood that the display 612 and I / O devices 614 are part of the control system 600. Furthermore, although the display 612, I / O devices 614, and cursor control 616 are illustrated as separate components, it is understood that they may be combined, such as a touch screen display.

[0069] In some embodiments, the control system 600 can be used to perform various functions described herein. According to some embodiments, this usage is provided by the control system 100 in response to the processing circuit device 604 executing one or more sequences of one or more instructions contained in the main memory 606. Those skilled in the art will know how to prepare such instructions based on the functions, algorithms and methods described herein. Such instructions can be read from another processor-readable medium (such as a storage device 610) into the main memory 606. The execution of the instruction sequence contained in the main memory 606 causes the processing circuit device 604 to perform the processing steps described herein. One or more processors in a multi-processing device can also be used to execute the instruction sequence contained in the main memory 606. In an alternative embodiment, a hard-wired circuit device can be used in place of a software instruction or in combination with a software instruction to implement various embodiments described herein. Therefore, the embodiment is not limited to any specific combination of hardware circuit devices and software.

[0070] Transmission media includes coaxial cables, copper wire and fiber optics, including the wires that make up bus 602. Transmission media can also take the form of acoustic or light waves, such as those generated during radio-wave and infrared data communications.

[0071] Various forms of processor-readable media may be used to carry one or more sequences of one or more instructions to the processing circuit device 604 for execution. For example, the instructions may initially be carried to a disk of a remote computer. The remote computer may load the instructions into its dynamic memory and send the instructions over a network (such as the Internet or a local network). A receiving unit local to the control system 600 may receive data from the network and provide the data on the bus 602. The bus 602 carries the data to the main memory 606, from which the processing circuit device 604 retrieves and executes the instructions. The instructions received by the main memory 606 may optionally be stored on the storage device 610 before or after execution by the processing circuit device 604.

[0072] The control system 600 also includes a communication interface 618 coupled to the bus 602. The communication interface 618 provides a two-way data communication coupled to a network link 620, which is connected to a local network 622. For example, the communication interface 618 can be an integrated services digital network (ISDN) card or a modem to provide a data communication connection to a corresponding type of telephone line. As another example, the communication interface 618 can be a local area network (LAN) card to provide a data communication connection to a compatible LAN. A wireless link can also be implemented. In any such implementation, the communication interface 618 sends and receives electrical, electromagnetic or optical signals carrying data streams representing various types of information.

[0073] The network link 620 generally provides data communication to other devices through one or more networks. For example, the network link 620 can provide a connection with a host computer 624 or equipment 626 (such as a radiation beam source or a switch operably coupled to the radiation beam source) through a local network 622. The data stream transmitted by the network link 620 may include electrical signals, electromagnetic signals, or optical signals. The signals through various networks and the signals on the network link 620 and the signals through the communication interface 618 (which carry data to and from the control system 600) are exemplary forms of carrier waves that transmit information. The control system 600 can send messages and receive data (including program code) through the network, the network link 620, and the communication interface 618.

[0074] Although the terms "first", "second", etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, the first element may be referred to as the second element, and similarly, the second element may be referred to as the first element without departing from the scope of this disclosure. As used herein, the term "and / or" includes any and all combinations of one or more items in the associated listed items.

[0075] When an element is referred to as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be intervening elements. Conversely, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements. Other words used to describe the relationship between elements should be interpreted in a similar manner (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.).

[0076] The terms used herein are only used to describe specific embodiments and are not intended to be limiting. As used herein, the singular forms "a", "an", and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It should be further understood that when used herein, the terms "include", "comprise", "have", and / or "contain" specify the presence of the features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0077] It should also be noted that in some alternative embodiments, the functions / actions may appear differently from the order shown in the figures. For example, two figures shown in succession may actually be performed substantially simultaneously, or may sometimes be performed in reverse order, depending on the functions / actions involved.

[0078] Specific details are provided in the following description to provide a comprehensive understanding of the example embodiments. However, those skilled in the art will appreciate that the example embodiments may be implemented without these specific details. For example, the system may be shown in block diagram form so as not to obscure the example embodiments with unnecessary details. In other cases, well-known processes, structures, and techniques may be shown without unnecessary details so as not to obscure the example embodiments.

[0079] As discussed herein, the illustrative embodiments are described with reference to symbolic representations of acts and operations (e.g., in the form of flow charts, flowcharts, data flow diagrams, structure diagrams, block diagrams, etc.), which may be implemented as program modules or functional processes, including routines, programs, objects, components, data structures, etc., that perform particular tasks or implement particular abstract data types, and may be implemented using existing hardware, such as processing or control circuitry, such as, but not limited to, one or more processors, one or more central processing units (CPUs), one or more controllers, one or more arithmetic logic units (ALUs), one or more digital signal processors (DSPs), one or more microcomputers, one or more field programmable gate arrays (FPGAs), one or more systems on chips (SoCs), one or more programmable logic units (PLUs), one or more microprocessors, one or more application specific integrated circuits (ASICs), or any other device or devices capable of responding to and executing instructions in a defined manner.

[0080] Although a flowchart may describe operations as a sequential process, many of the operations may be performed in parallel, concurrently, or simultaneously. In addition, the order of the operations may be rearranged. A process may terminate when its operations are completed, but may also have additional steps not included in the diagram. A process may correspond to a method, function, procedure, subroutine, subprogram, etc. When a process corresponds to a function, its termination may correspond to the function returning to the calling function or the main function.

[0081] As disclosed herein, the terms "memory", "storage medium", "processor-readable medium", "computer-readable storage medium" or "non-transitory computer-readable storage medium" may refer to one or more devices for storing data, including read-only memory (ROM), random access memory (RAM), magnetic RAM, core memory, magnetic disk storage media, optical storage media, flash memory devices and / or other tangible machine-readable media for storing information. The term "computer-readable medium" may include, but is not limited to, portable or fixed storage devices, optical storage devices, and various other media capable of storing, containing or carrying instructions and / or data.

[0082] In addition, the example embodiments may be implemented by hardware, software, firmware, middleware, microcode, hardware description language, or any combination thereof. When implemented in software, firmware, middleware, or microcode, the program code or code segments for performing the necessary tasks may be stored in a machine or computer readable medium, such as a computer readable storage medium. When implemented in software, one or more processors will perform the necessary tasks. For example, as described above, according to one or more example embodiments, at least one memory may include or store computer program code, and at least one memory and computer program code may be configured to enable a network element or network device to perform the necessary tasks together with at least one processor. In addition, the processor, memory, and example algorithm are encoded as computer program code, used as a means to provide or cause the execution of the operations discussed herein.

[0083] As used herein, the terms "including" and / or "having" are defined as comprising (i.e., open language). As used herein, the term "coupled" is defined as connected, although not necessarily directly and not necessarily mechanically. Terms derived from the word "indicate" are intended to cover all of the various techniques that can be used to communicate or reference the indicated object / information. Some (but not all) examples of techniques that can be used to communicate or reference the indicated object / information include: communication of the indicated object / information, communication of an identifier of the indicated object / information, communication of information used to generate the indicated object / information, communication of some portion or part of the indicated object / information, communication of some derivative of the indicated object / information, and communication of some symbols representing the indicated object / information.

[0084] The benefits, other advantages and solutions to problems have been described above with respect to specific embodiments. However, the benefits, advantages, solutions to problems and any elements that may cause or produce such benefits, advantages or solutions or make such benefits, advantages or solutions more obvious should not be construed as key, required or essential features or elements of any or all claims.

[0085] Non-limiting illustrative embodiments

[0086] Illustrative Embodiments 1. A radiation therapy system comprising:

[0087] An X-ray target is configured to convert an electron beam into an X-ray beam, the X-ray target comprising,

[0088] A plurality of target layers, each of the plurality of target layers being configured to convert a portion of the electron beam into a portion of the X-ray beam.

[0089] Illustrative embodiment 2. The radiation therapy system according to illustrative embodiment 1, wherein the diameter of each target layer in the plurality of target layers corresponds to the divergence of the beam spot size.

[0090] Illustrative Embodiment 3. The radiation therapy system of any one of Illustrative Embodiments 1-2, wherein the radiation therapy system is configured to: control the electron beam so that the X-ray beam delivers a radiation rate of at least 40 Gray / second (Gy / s).

[0091] Illustrative Embodiment 4. The radiation therapy system of any one of Illustrative Embodiments 1-2, wherein the radiation therapy system is configured to: control the electron beam so that the X-ray beam delivers a radiation rate of at least 1 Gray / second (Gy / s).

[0092] Illustrative Embodiment 5. The radiation therapy system of any one of Illustrative Embodiments 1-4, wherein the plurality of target layers are stacked in series.

[0093] Illustrative Embodiment 6. The radiation therapy system of Illustrative Embodiment 5, wherein the plurality of target layers are spaced apart by the same distance.

[0094] Illustrative embodiment 7. A radiation therapy system according to illustrative embodiment 5, wherein a first distance between a first target layer among the multiple target layers and a second target layer among the multiple target layers is different from a second distance between the second target layer among the multiple target layers and a third target layer among the multiple target layers.

[0095] Illustrative Embodiment 8. The radiation therapy system of any one of Illustrative Embodiments 1-7, wherein the plurality of target layers comprises at least one of the following: tantalum (Ta) or tungsten (W).

[0096] Illustrative Embodiment 9. The radiation therapy system of any one of Illustrative Embodiments 1-8, further comprising a heat transfer material located between at least two target layers of the X-ray target.

[0097] Illustrative Embodiment 10. The radiation therapy system of Illustrative Embodiment 9, wherein the heat transfer material has a high thermal conductivity.

[0098] Illustrative Embodiment 11. The radiation therapy system of any of Illustrative Embodiments 9-10, wherein the heat transfer material comprises copper.

[0099] Illustrative embodiment 12. The radiation therapy system according to any one of illustrative embodiments 1-11, further comprising:

[0100] A plurality of heat transfer material layers are respectively associated with the plurality of target layers, each heat transfer material layer and the corresponding target layer form a paired layer, wherein the paired layers are spaced apart along a central axis of the electron beam.

[0101] Illustrative Embodiment 13. The radiation therapy system of Illustrative Embodiment 12, wherein the paired layers are equally spaced apart.

[0102] Illustrative embodiment 14. The radiation therapy system according to any one of illustrative embodiments 1-13, further comprising:

[0103] A plurality of heat dissipation layers respectively receive the plurality of target layers, each heat dissipation layer and a corresponding target layer form a paired layer, wherein the paired layers are spaced apart along a central axis of the electron beam.

[0104] Illustrative embodiment 15. The radiation therapy system according to illustrative embodiment 14, wherein each heat dissipation layer includes a receiving area having a size corresponding to the corresponding target layer.

[0105] Illustrative embodiment 16. The radiation therapy system according to any one of illustrative embodiments 14-15, further comprising:

[0106] At least one cooling device is coupled to at least one of the paired layers and is configured to provide a cooling fluid.

[0107] Illustrative Embodiment 17. The radiation therapy system of Illustrative Embodiment 16, wherein the at least one cooling device is a tube.

[0108] Illustrative Embodiment 18. The radiation therapy system of any of Illustrative Embodiments 14-17, wherein the at least one paired layer defines a channel in an associated heat sink layer to receive the cooling fluid.

[0109] Illustrative Embodiment 19. The radiation therapy system of any of Illustrative Embodiments 1-18, wherein the X-ray target is configured to absorb at least 90% of the electrons in the electron beam that are incident on the X-ray target.

[0110] Illustrative Embodiment 20. The radiation therapy system of Illustrative Embodiment 19, wherein the X-ray target is configured to absorb at least 99% of the electrons in the incident electron beam.

[0111] Illustrative Embodiment 21. The radiation therapy system of any one of Illustrative Embodiments 1-20, wherein the number of the plurality of target layers of the X-ray target is adjustable based on the energy of the electron beam.

Claims

1. A radiotherapy system comprising: An X-ray target is configured to convert an electron beam into an X-ray beam, the X-ray target comprising, A plurality of target layers, each of the plurality of target layers being configured to convert a portion of the electron beam into a portion of the X-ray beam.

2. The radiation therapy system of claim 1, wherein a diameter of each of the plurality of target layers corresponds to a divergence of a beam spot size.

3. The radiation therapy system of claim 1, wherein the radiation therapy system is configured to control the electron beam so that the X-ray beam delivers a radiation rate of at least 40 Gray / second (Gy / s).

4. The radiation therapy system of claim 1, wherein the radiation therapy system is configured to control the electron beam so that the x-ray beam delivers a radiation rate of at least 1 Gray / second (Gy / s).

5. The radiation therapy system of claim 1, wherein the plurality of target layers are stacked in series.

6. The radiation therapy system of claim 5, wherein the plurality of target layers are spaced the same distance apart.

7. The radiation therapy system of claim 5, wherein a first distance between a first target layer among the plurality of target layers and a second target layer among the plurality of target layers is different from a second distance between the second target layer among the plurality of target layers and a third target layer among the plurality of target layers.

8. The radiation therapy system of claim 1, wherein the plurality of target layers comprises at least one of: tantalum (Ta) or tungsten (W).

9. The radiation therapy system of claim 1 , further comprising: The heat transfer material is located between at least two target layers of the X-ray target.

10. The radiation therapy system of claim 9, wherein the heat transfer material has a high thermal conductivity.

11. The radiation therapy system of claim 10, wherein the heat transfer material comprises copper.

12. The radiation therapy system of claim 1 , further comprising: A plurality of heat transfer material layers are respectively associated with the plurality of target layers, each heat transfer material layer and the corresponding target layer form a paired layer, wherein the paired layers are spaced apart along a central axis of the electron beam.

13. The radiation therapy system of claim 12, wherein the paired layers are equally spaced apart.

14. The radiation therapy system of claim 1 , further comprising: A plurality of heat dissipation layers respectively receive the plurality of target layers, each heat dissipation layer and a corresponding target layer form a paired layer, wherein the paired layers are spaced apart along a central axis of the electron beam.

15. The radiation therapy system of claim 14, wherein each heat sink layer comprises a receiving region having a size corresponding to the corresponding target layer.

16. The radiation therapy system of claim 14, further comprising: At least one cooling device is coupled to at least one of the paired layers and is configured to provide a cooling fluid.

17. The radiation therapy system of claim 16, wherein the at least one cooling device is a tube.

18. The radiation therapy system of Claim 16, wherein the at least one paired layer defines a channel in an associated heat sink layer to receive the cooling fluid.

19. The radiation therapy system of claim 1, wherein the X-ray target is configured to absorb at least 90% of electrons in the electron beam that are incident on the X-ray target.

20. The radiation therapy system of claim 19, wherein the x-ray target is configured to absorb at least 99% of the electrons in the incident electron beam.

21. The radiation therapy system of claim 20, wherein the number of the plurality of target layers of the X-ray target is adjustable based on the energy of the electron beam.

Images