Radiation therapy device and method

Abstract

To increase accuracy of an exposure dose.SOLUTION: Radiotherapy equipment according to an embodiment comprises an irradiation part, a measurement part and a control part. The irradiation part applies radiation. The measurement part measures a dose of the radiation, which is applied from the irradiation part, with time. The control part controls radiation irradiation until the dose reaches a target dose, on the basis of the dose of the radiation measured with time.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The embodiments disclosed in the present specification and drawings include a radiation therapy device and How to eat Regarding the law. [Background technology]

[0002] In recent years, the FLASH irradiation method has become known in radiation therapy, in which ultra-high dose rates of radiation, several hundred to a thousand times higher than the dose rates of conventional radiation therapy, are irradiated to the radiation irradiation area. The FLASH irradiation method has attracted attention as a method that can suppress the occurrence of damage to normal tissues without changing the effect of radiation therapy on the target tissue. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-189527 A Summary of the Invention [Problem to be solved by the invention]

[0004] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to improve the accuracy of the irradiation dose. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described later can also be positioned as other problems. [Means for solving the problem]

[0005] A radiation therapy device according to an embodiment includes an irradiation unit, a measurement unit, and a control unit. The irradiation unit irradiates radiation. The measurement unit measures the dose of radiation irradiated from the irradiation unit over time. The control unit controls the irradiation of radiation until a target dose is reached based on the dose of radiation measured over time. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a radiation therapy system according to the first embodiment. [Diagram 2] FIG. 2 is an external view showing an example of the radiotherapy apparatus according to the first embodiment. [Diagram 3] FIG. 3 is a diagram showing an example of the configuration of the radiotherapy apparatus according to the first embodiment. [Figure 4] FIG. 4 is a diagram for explaining control by the control function according to the first embodiment. [Diagram 5] FIG. 5 is a flowchart showing a processing procedure performed by the radiotherapy apparatus according to the first embodiment. [Figure 6] FIG. 6 is a diagram for explaining control by the control function according to the second embodiment. [Figure 7] FIG. 7 is a flowchart showing a processing procedure performed by the radiotherapy apparatus according to the second embodiment. [Figure 8] FIG. 8 is a diagram for explaining an example of a process by a control function according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, the embodiments of the radiotherapy apparatus and radiotherapy method according to the present application will be described in detail with reference to the accompanying drawings. Note that the radiotherapy apparatus and radiotherapy method according to the present application are not limited to the embodiments shown below. In addition, the embodiments can be combined with other embodiments or conventional techniques as long as there is no contradiction in the processing content.

[0008] (First embodiment) First, a radiation therapy system including a radiation therapy apparatus according to the present embodiment will be described. FIG. 1 is a diagram showing an example of the configuration of a radiation therapy system 1 according to the first embodiment. As shown in FIG. 1, the radiation therapy system 1 according to the first embodiment includes a treatment planning CT (Computed Tomography) apparatus 100, a treatment planning apparatus 200, a radiation therapy information system 300, and a radiation therapy apparatus 400. The treatment planning CT apparatus 100, the treatment planning apparatus 200, the radiation therapy information system 300, and the radiation therapy apparatus 400 are connected to each other so as to be able to communicate with each other via a network 2. Note that the configuration shown in FIG. 1 is merely an example, and the embodiment is not limited thereto. For example, the radiation therapy system 1 may include various other apparatuses and systems.

[0009] The treatment planning CT device 100 has a gantry, a bed device with a top plate, and a console, and collects CT image data including a treatment target site (such as a tumor) of a subject lying on the top plate, and transmits the collected CT image data to the treatment planning device 200. Specifically, the treatment planning CT device 100 collects projection data while rotating an X-ray tube and an X-ray detector provided on the gantry around the subject, and reconstructs three-dimensional CT image data based on the collected projection data. Here, the top plate in the treatment planning CT device 100 has a planar shape similar to the top plate of a radiation therapy device.

[0010] In this embodiment, only the treatment planning CT device 100 is shown as a device for collecting image data for treatment planning, but the embodiment is not limited to this. For example, three-dimensional image data for treatment planning may be collected by a treatment planning MRI (Magnetic Resonance Imaging) device, an X-ray diagnostic device capable of outputting three-dimensional images, an ultrasonic diagnostic device, or the like.

[0011] The treatment planning device 200 uses three-dimensional CT image data of the treatment target collected by the treatment planning CT device 100 to make a treatment plan for radiation therapy by the radiation therapy device 400. For example, the treatment planning device 200 identifies the position of a treatment target area in the treatment target body using the CT image data collected by the treatment planning CT device 100. In addition, for example, the treatment planning device 200 makes a plan for the irradiation angle of radiation to be irradiated by the radiation therapy device 400 to the treatment target area whose position is identified using the CT image data, the dose and shape of the irradiation field for each irradiation angle, the number of irradiations, etc. Then, the treatment planning device 200 transmits the treatment plan to the radiation therapy information system 300 and the radiation therapy device 400.

[0012] The radiotherapy information system 300 stores and manages various information related to radiotherapy. Specifically, the radiotherapy information system 300 stores and manages various information related to the progress of treatment for each treated subject, such as a treatment plan, performance information (irradiation history), various reports, and records of the condition of the treated subject. The radiotherapy information system 300 can be accessed by each device connected to the network 2 and provide the information it manages.

[0013] The radiotherapy device 400 performs radiotherapy by irradiating radiation to a subject according to a treatment plan by the treatment planning device 200. Here, the radiotherapy device 400 according to the present embodiment is a radiotherapy device capable of irradiating radiation by a FLASH irradiation method in which an ultra-high dose rate, which is several hundred to a thousand times higher than the dose rate of normal radiotherapy, is irradiated to an irradiation area. The radiotherapy device 400 according to the present embodiment may irradiate any of electron beams, X-rays, gamma rays, proton beams, and heavy particle beams.

[0014] FIG. 2 is an external view showing an example of a radiotherapy device 400 according to the first embodiment. FIG. 2 shows the radiotherapy device 400 installed in a treatment room. As shown in FIG. 2, the radiotherapy device 400 includes a gantry having a radiation generator 412, a radiation aperture 414, and an imaging device (an X-ray generator 411a and an X-ray detector 411b), and a bed device having a tabletop 422, and performs radiotherapy based on control from a console (not shown). Specifically, the radiotherapy device 400 acquires a treatment plan from the radiotherapy information system 300. Then, the radiotherapy device 400 rotates the gantry in the direction of the arrow to set an irradiation angle according to the treatment plan, and performs radiation irradiation on a subject lying on the tabletop 422.

[0015] In radiation therapy, first, three-dimensional CT image data required for creating a treatment plan is collected by the treatment planning CT device 100. In this case, a fixture may be created to improve the reproducibility and maintainability of the posture of the treatment subject. Also, marks required for positioning to accurately irradiate radiation in each radiation therapy session may be attached to the surface of the treatment subject.

[0016] Then, in the treatment plan, the radiation irradiation area, the radiation irradiation angle, the dose and the shape of the irradiation field for each irradiation angle, the number of irradiations, etc. are determined. For example, in determining the radiation irradiation area, first, a risk organ to which radiation should be avoided is set based on CT image data collected by the treatment planning CT device 100. Then, a gross tumor volume (GTV), which is a three-dimensional area in which the progression or existence of a tumor can be confirmed with the naked eye, is set, and a clinical target volume (CTV) including the set GTV and a potential tumor area that cannot be confirmed with the naked eye is set. The risk organ, GTC, and CTV are set by, for example, contouring (extraction of a contour), and the contouring can be performed either manually by a doctor or automatically by image processing technology.

[0017] In determining the radiation irradiation area, an internal target volume (ITV) including an internal margin (IM) to absorb the effects of internal organ movements such as breathing, swallowing, cardiac pulsation, peristalsis, etc. is set for the CTV. Furthermore, a planning target volume (PTV) including a set-up margin (SM) for each irradiation is set for the CTV, thereby determining the radiation irradiation area.

[0018] In this way, when the radiation irradiation region is determined, the radiation irradiation conditions for the determined irradiation region are set. For example, in the treatment planning device 200, an operator (medical worker) sets irradiation conditions such as the radiation irradiation angle, the dose for each irradiation angle, the shape of the irradiation field, and the number of irradiations. Here, the shape of the irradiation field is formed by, for example, a multi-leaf collimator (MLC) which is the radiation constrictor 414. The MLC has a plurality of radiation shielding plates which set the radiation irradiation range, and each shielding plate is independently driven based on the treatment plan, thereby forming an irradiation field which matches the shape of the radiation irradiation region (PTV).

[0019] The treatment plan created in this manner is transmitted to the radiation therapy information system 300 and managed together with patient information, treatment history, etc. During radiation therapy, the treatment plan is transmitted from the radiation therapy information system 300 to the radiation therapy device 400. The radiation therapy device 400 irradiates radiation to the subject lying on the tabletop 422 in accordance with the received treatment plan.

[0020] Here, the position of the subject lying on the tabletop 422 is adjusted so that the subject is in the same position as when the CT image data for the treatment plan was collected, and a rough alignment is performed by adjusting the position of the subject and the bed so that the mark on the subject's surface overlaps with the laser from the laser sight.

[0021] Thereafter, the radiotherapy device 400 generates cone beam CT image data for alignment by an imaging device including an X-ray generator 411a and an X-ray detector 411b in order to align the radiation irradiation area with the isocenter of the radiotherapy device 400. For example, the radiotherapy device 400 irradiates X-rays from the X-ray generator 411a while rotating the gantry, collects projection data for an angle of 200 degrees or more, and reconstructs three-dimensional cone beam CT image data based on the collected projection data.

[0022] The radiotherapy device 400 performs alignment between the irradiation area and the isocenter using the reconstructed cone beam CT image data and the CT image data for the treatment plan. The radiotherapy device 400 can perform alignment by other methods in addition to the above-mentioned alignment using the cone beam CT image data. For example, as shown in FIG. 2, two X-ray imaging devices 411c are installed in the treatment room as imaging devices. The radiotherapy device 400 performs alignment between the irradiation area and the isocenter by photographing the treatment subject lying on the top board 422 with the two X-ray imaging devices 411c and comparing the obtained X-ray images in two directions with a DRR (Digitally Reconstructed Radiograph) generated from the CT image data for the treatment plan. The DRR is a virtual X-ray image obtained by projecting the CT image data for the treatment plan in two directions photographed by the two X-ray imaging devices 411c.

[0023] Thus, in radiation therapy, in order to irradiate radiation in accordance with a treatment plan, detailed positioning is performed and the radiation irradiation dose and the like are strictly controlled. Here, when irradiating radiation using the above-mentioned FLASH irradiation method, since the radiation dose rate is very high (for example, several hundred to several thousand times higher than normal), it is necessary to adjust the radiation irradiation time with a precision several hundred to several thousand times higher. Furthermore, since the radiation dose rate is not always constant but fluctuates, it is necessary to further adjust the radiation irradiation time in accordance with the fluctuation of the dose rate. In other words, since the radiation used in the FLASH irradiation method has a high dose rate, even a slight deviation in the irradiation time significantly affects the irradiation dose.

[0024] Therefore, the radiation therapy device 400 according to the present embodiment monitors the radiation irradiated from the radiation generator in real time, and adjusts the radiation irradiation time based on the monitoring result, thereby improving the accuracy of the irradiation dose. Specifically, the radiation therapy device 400 according to the present embodiment monitors the dose rate and the accumulated dose of the radiation irradiated from the radiation generator in real time, and stops the irradiation of the radiation when the target dose is reached, thereby improving the accuracy of the irradiation dose.

[0025] Hereinafter, the radiotherapy device 400 according to this embodiment will be described in detail. Fig. 3 is a diagram showing an example of the configuration of the radiotherapy device 400 according to the first embodiment. As shown in Fig. 3, the radiotherapy device 400 includes a gantry 410, a bed device 420, and a console 430.

[0026] The gantry 410 includes an imaging device 411, a radiation generator 412, a dosimeter 413, and a radiation aperture 414. The imaging device 411 includes an X-ray generator 411a and an X-ray detector 411b, and performs imaging to collect cone beam CT image data of a treatment subject placed on the bed device 420 under the control of the console 430. Specifically, the imaging device 411 is arranged such that an X-ray generator 411a for irradiating X-rays for imaging and an X-ray detector 411b for detecting X-rays for imaging face each other across the treatment subject. The imaging device 411 irradiates X-rays from the X-ray generator 411a and detects the X-rays with the X-ray detector 411b while the gantry 410 is rotating, thereby collecting projection data for an angle of 200 degrees or more. The imaging device 411 transmits the collected projection data to the console 430.

[0027] The radiation generator 412 includes an electron gun and an acceleration tube, not shown. The acceleration tube accelerates thermoelectrons generated from the electron gun and causes them to collide with a tungsten target to emit radiation for treatment. Here, the radiation generator 412 can generate a dose of radiation that enables radiation irradiation by the FLASH irradiation method. The radiation generator 412 is an example of an irradiation unit.

[0028] The dosimeter 413 measures the dose of radiation radiated by the radiation generator 412. Specifically, the dosimeter 413 measures the dose of radiation radiated by the radiation generator 412 over time. For example, the dosimeter 413 is a dosimeter such as an ion chamber, and is installed between the radiation generator 412 and the radiation constrictor 414 to measure the dose of incident radiation. The dosimeter 413 is an example of a measuring unit.

[0029] The radiation constrictor 414 is, for example, an MLC, and has a plurality of radiation shielding plates for setting an irradiation range of therapeutic radiation. For example, the radiation constrictor 414 forms a radiation irradiation field having a shape corresponding to an irradiation region of a treatment target by independently moving a plurality of radiation shielding plates by a moving mechanism (not shown) in response to control from the console 430.

[0030] The bed device 420 has a base 421 and a top plate 422. The base 421 has a built-in bed driving device 423 and movably supports the top plate 422. The top plate 422 has a flat shape, and a subject to be treated is placed on it. The bed driving device 423 includes a motor, an actuator, etc., and moves the top plate 422 under the control of the console 430.

[0031] The console 430 includes a communication interface 431 , an input interface 432 , a display 433 , a memory circuit 434 , and a processing circuit 435 .

[0032] The communication interface 431 is connected to the processing circuit 435, and controls the transmission and communication of various data between each device connected via the network 2. For example, the communication interface 431 is realized by a network card, a network adapter, a NIC (Network Interface Controller), or the like.

[0033] The input interface 432 is connected to the processing circuit 435, converts an input operation received from an operator (medical worker) into an electrical signal, and outputs the signal to the processing circuit 435. Specifically, the input interface 432 converts an input operation received from an operator into an electrical signal, and outputs the signal to the processing circuit 435. For example, the input interface 432 is realized by a trackball, a switch button, a mouse, a keyboard, a touch pad that performs an input operation by touching the operation surface, a touch screen in which a display screen and a touch pad are integrated, a non-contact input circuit using an optical sensor, and a voice input circuit. In this specification, the input interface 432 is not limited to only those that have physical operation parts such as a mouse and a keyboard. For example, an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the device and outputs the electrical signal to a control circuit is also included in the input interface 432.

[0034] The display 433 is connected to the processing circuitry 435 and displays various information and various image data output from the processing circuitry 435. For example, the display 433 is realized by a liquid crystal display, a CRT (Cathode Ray Tube) display, an organic EL display, a plasma display, a touch panel, or the like. In this embodiment, for example, the display 433 displays a treatment plan, an irradiation history, and the like. The display 433 also displays information such as an irradiation status.

[0035] The memory circuitry 434 is connected to the processing circuitry 435 and stores various data. For example, the memory circuitry 434 is realized by a semiconductor memory element such as a random access memory (RAM) or a flash memory, a hard disk, an optical disk, or the like. As an example, the memory circuitry 434 stores a response time 434a, an irradiation history 434b, and the like. The memory circuitry 434 also stores a treatment plan received from the radiation therapy information system 300, various processing results, and the like. The memory circuitry 434 also stores programs corresponding to various functions executed by the processing circuitry 435.

[0036] The response time 434a is the time from the transmission of a control signal in the device to the actual control being performed. For example, the response time 434a is the time from the transmission of a control signal (irradiation stop command) for stopping the emission of radiation to the ray generator 412 to the actual stopping of radiation.

[0037] The irradiation history 434b includes irradiation conditions of radiation actually irradiated to the treated object, a dose distribution, and the like, and is stored in the memory circuitry 434 every time radiation irradiation is performed. The irradiation history 434b is transmitted to the radiation therapy information system 300 every time radiation irradiation is completed, and is managed by the radiation therapy information system 300.

[0038] The processing circuitry 435 controls the operation of the entire radiotherapy apparatus 400 in response to an input operation received from an operator via the input interface 432. For example, the processing circuitry 435 is realized by a processor. As shown in Fig. 3, the processing circuitry 435 executes a control function 435a, an acquisition function 435b, an imaging function 435c, and a reconstruction function 435d. Here, the control function 435a is an example of a control unit.

[0039] The control function 435a controls to execute processes according to various requests input via the input interface 432. For example, the control function 435a controls transmission and reception of information (e.g., treatment plan, irradiation history, etc.) via the communication interface 431, storage of information in the memory circuitry 434, display of information on the display 433, etc.

[0040] Moreover, the control function 435a controls the rotation of the gantry 410, the irradiation of radiation by the radiation generator 412, the movement of the radiation shielding plate in the radiation constrictor 414, etc., by transmitting a control signal based on the treatment plan. Furthermore, the control function 435a controls the bed driving device 423 in the bed device 420, and controls the movement of the tabletop 422, by transmitting a control signal based on the treatment plan.

[0041] Here, the control function 435a can control radiation irradiation by the FLASH irradiation method. That is, the control function 435a can control the radiation generator 412 to irradiate radiation at a high dose rate. Furthermore, the control function 435a calculates the accumulated dose and dose rate of radiation irradiated from the radiation generator 412 based on information on the dose of radiation acquired by the acquisition function 435b, and controls the radiation generator 412 to stop the irradiation of radiation based on the calculated accumulated dose and dose rate. The above control will be described in detail later.

[0042] The acquisition function 435b acquires information on the dose measured by the dosimeter 413. Specifically, the acquisition function 435b acquires information on the dose measured by the dosimeter 413 for radiation irradiated from the radiation generator 412. For example, the acquisition function 435b acquires information on the dose periodically measured by the dosimeter 413.

[0043] The imaging function 435c controls the imaging device 411 to collect projection data for reconstructing cone beam CT image data. Specifically, the imaging function 435c controls the rotation of the gantry 410, the irradiation of X-rays by the X-ray generator 411a, and the data collection by the X-ray detector 411b. For example, the imaging function 435c rotates the gantry 410 by 200 degrees or more, causes the X-ray generator 411a to irradiate X-rays, and collects data by the X-ray detector 411b, thereby collecting projection data for an angle of 200 degrees or more around the treatment subject. Then, the imaging function 435c stores the collected projection data in the memory circuitry 434.

[0044] In addition, when two X-ray imaging devices 411c are installed in the treatment room, the imaging function 435c controls the two X-ray imaging devices 411c to collect X-ray images from two directions and store the collected X-ray images from two directions in the memory circuit 434.

[0045] The reconstruction function 435d generates various images from the projection data collected by the imaging function 435c, and stores the generated images in the memory circuitry 434. For example, the reconstruction function 435d reconstructs cone beam CT image data by reconstructing the projection data using various reconstruction methods, and stores the reconstructed cone beam CT image data in the memory circuitry 434.

[0046] The control function 435a uses the reconstructed cone beam CT image data and the CT image data for treatment planning to align the irradiation area with the isocenter, and controls the irradiation of radiation to the irradiation area.

[0047] Here, the control function 435a monitors the dose in real time in the irradiation of radiation by the FLASH irradiation method, and controls the irradiation of radiation based on the monitoring result, thereby improving the accuracy of the irradiation dose. Specifically, the control function 435a controls the irradiation of radiation until a target dose is reached based on the dose of radiation measured over time. More specifically, the control function 435a calculates the accumulated dose and dose rate of radiation irradiated from the radiation generator 412 based on the dose of radiation measured over time, and controls the dose rate of radiation irradiated until the target dose is reached based on the accumulated dose and dose rate. For example, the control function 435a calculates the accumulated dose and dose rate of radiation irradiated from the radiation generator 412 from the dose of radiation measured by the dosimeter 413, and controls the radiation generator 412 to stop the irradiation of radiation based on the calculated accumulated dose and dose rate.

[0048] That is, the control function 435a calculates the cumulative dose irradiated to the irradiation area and the dose per unit time based on the dose of radiation measured by the dosimeter 413. Then, the control function 435a determines whether to stop the irradiation of radiation based on the calculated cumulative dose and dose rate and the target dose to be irradiated to the irradiation area, and stops the irradiation of radiation based on the determination result.

[0049] For example, the control function 435a predicts remaining irradiation information indicating at least one of the remaining irradiation dose, which is the remaining irradiation dose until the target dose (target exposure dose), and the remaining irradiation time, which is the time until the target dose is reached, from the accumulated dose of radiation and the dose rate, and controls the radiation generator 412 to stop irradiating radiation based on the prediction result.

[0050] Fig. 4 is a diagram for explaining the control by the control function 435a according to the first embodiment. In Fig. 4, the total dose (accumulated dose) of radiation irradiated to the irradiation area is shown on the vertical axis, and the irradiation time is shown on the horizontal axis. Also, in Fig. 4, the value of the accumulated dose calculated based on the dose measured by the dosimeter 413 is shown by plotting black circles. Note that, for the sake of convenience in Fig. 4, the intervals between the plotting black circles are shown to be wide, but in reality, the dose is measured more frequently.

[0051] For example, as shown in the first diagram of FIG. 4, the control function 435a calculates an integrated dose based on information on the dose measured by the dosimeter 413 after radiation irradiation has started. As an example, the control function 435a calculates an integrated dose shown by a black circle plot in the first diagram of FIG. 4 based on the measurement result of the first measurement (measurement at time t1 in the diagram) and the measurement result of the next measurement after radiation irradiation has started. Here, the control function 435a can predict the remaining exposure dose from the calculated integrated dose and the target dose ("a" in the diagram). That is, the control function 435a calculates the remaining exposure dose by subtracting the integrated dose from the target dose.

[0052] Furthermore, the control function 435a calculates the dose rate at the time based on the dose measured by the dosimeter 413 and the time when the dose was measured (radiation irradiation time). That is, the control function 435a calculates the slope of the solid line in the graph shown in Fig. 4. Here, the control function 435a can predict the remaining irradiation time from the calculated dose rate and the target dose ("a" in the figure). That is, the control function 435a calculates the time required to reach the target dose when irradiation is continued at the dose rate calculated immediately before (in the case of irradiation shown by the dashed line in the figure).

[0053] Here, the control function 435a can perform control so as to predict the remaining irradiation information using the radiation dose measured after a predetermined period has elapsed since the start of irradiation of radiation. For example, the control function 435a calculates the remaining irradiation information using the measurement results thereafter, without using the dose measured up to "time t1" shown in the first diagram of FIG. 4. The radiation generator 412 may have an unstable output at the start of irradiation of radiation, resulting in a low dose rate. Therefore, the control function 435a calculates the remaining irradiation information using the dose information measured after the output of the radiation generator 412 becomes stable, without using the dose information measured during such a period.

[0054] The stability of the output from the radiation generator 412 may be determined by a preset time, or may be determined based on the dose measured by the dosimeter 413. For example, when the time is set in advance, the control function 435a calculates the remaining irradiation information using the dose measured after a preset time has elapsed after the start of irradiation of radiation. Also, for example, when the stability is based on the dose measured by the dosimeter 413, the control function 435a calculates the dose rate after the start of irradiation of radiation, and determines that the output is stable when the value of the dose rate exceeds a threshold, and calculates the remaining irradiation information using the dose measured thereafter.

[0055] Then, as shown in the second and third diagrams in Fig. 4, the control function 435a calculates the remaining irradiation information each time the dose is measured by the dosimeter 413 (each time the measurement result is acquired by the acquisition function 435b). Here, the radiation irradiated by the radiation generator 412 varies in dose rate (slope of the solid line) as shown in the solid line graph in Fig. 4. The control function 435a monitors the change in this dose rate in real time and calculates the remaining irradiation information according to the change each time. As a result, the remaining exposure dose and remaining irradiation time calculated by the control function 435a become more accurate information.

[0056] Then, the control function 435a controls the radiation generator 412 to stop irradiating radiation when the remaining irradiation information becomes "0". That is, the control function 435a transmits a control signal to the radiation generator 412 to stop irradiating radiation when the remaining irradiation dose or remaining irradiation time becomes "0". This allows the control function 435a to improve the accuracy of the dose actually irradiated to the treatment target.

[0057] Here, the control function 435a predicts the remaining irradiation information based on the dose of radiation irradiated during the response time from the time when an irradiation stop command to stop irradiation of radiation is issued until the radiation is stopped, and the accumulated dose and dose rate. There is a certain response time from when a control signal is transmitted by the control function 435a until the radiation irradiation by the radiation generator 412 actually stops. In other words, the radiation is not immediately stopped at the time when the control function 435a transmits the control signal, but the radiation continues to be irradiated until the radiation irradiation is actually stopped after the control signal is transmitted.

[0058] Therefore, the control function 435a transmits a control signal for stopping radiation irradiation, taking into consideration the radiation irradiated during the response time. Specifically, the control function 435a transmits a control signal for stopping radiation irradiation when the accumulated dose obtained by subtracting the dose of radiation irradiated during the response time from the target dose is reached.

[0059] For example, as shown in the fourth diagram of Fig. 4, the control function 435a sets the value (plotted by the white circle in the diagram) obtained by subtracting the dose of radiation irradiated during the response time from the target dose "a" as a provisional target dose. Then, when the integrated dose of radiation calculated in real time reaches the provisional target dose, the control function 435a transmits a control signal for stopping radiation irradiation. That is, the control function 435a calculates remaining irradiation information up to the provisional target dose, and transmits a control signal for stopping radiation irradiation when the calculated remaining irradiation information becomes "0".

[0060] Here, the control function 435a acquires the response time 434a stored by the memory circuitry 434, and calculates the dose according to the acquired response time. For example, the control function 435a calculates the dose when radiation is irradiated at the current dose rate during the period (time t2 to time t3 in the figure) corresponding to the response time 434a acquired from the memory circuitry 434. Then, the control function 435a calculates a provisional target dose by subtracting the calculated dose from the target dose. That is, the control function 435a can appropriately set the provisional target dose according to the fluctuation of the dose rate during radiation irradiation. As a result, the control function 435a can further improve the accuracy of the irradiation dose.

[0061] The control function 435a stores the cumulative dose irradiated by the above-mentioned control in the memory circuitry 434 as an irradiation history.

[0062] As described above, the control function 435a monitors the radiation dose in real time and controls the stop of radiation irradiation based on the monitoring result, but can also perform various other controls. For example, the control function 435a controls the radiation generator 412 to stop the irradiation of radiation when the dose rate based on the dose measured by the dosimeter 413 falls below a threshold. That is, when performing radiation irradiation by the FLASH irradiation method, the control function 435a stops the irradiation of radiation by the FLASH irradiation method when the dose rate of radiation from the radiation generator 412 is significantly lower than a set value. As an example, the control function 435a stops the irradiation of radiation by the FLASH irradiation method by an interlock mechanism that does not irradiate radiation when the dose rate of radiation from the radiation generator 412 does not satisfy a condition.

[0063] In this way, the control function 435a monitors the radiation dose in real time, and controls the radiation irradiation by the FLASH irradiation method to stop when the dose rate condition in the FLASH irradiation method is not satisfied (when the dose rate is low for the FLASH irradiation method). In the FLASH irradiation method, when the radiation dose rate is low, there is a risk that the effect of the radiation therapy on the target tissue remains unchanged, and the advantage of suppressing the occurrence of damage in normal tissues is lost. Therefore, by the control function 435a controlling the radiation irradiation by the FLASH irradiation method to stop when the dose rate condition is not satisfied, it is possible to ensure higher safety and effectiveness in the radiation irradiation by the FLASH irradiation method.

[0064] Here, when irradiation of radiation by the FLASH irradiation method is stopped by the interlock mechanism, the control function 435a can also cause the display 433 to display information indicating the situation.

[0065] Furthermore, in a case where the output of radiation irradiation by the radiation generator 412 can be changed in real time, the control function 435a can also change the output of radiation irradiation by the radiation generator 412 in accordance with a dose rate based on the dose measured by the dosimeter 413. That is, the control function 435a can control so as to change the dose rate of radiation irradiated from the radiation generator 412 based on the calculated dose rate every time the dose is measured by the dosimeter 413. For example, when the dose rate based on the dose measured by the dosimeter 413 falls below a threshold value, the control function 435a controls the radiation generator 412 to increase the dose of radiation. That is, when radiation irradiation is performed by the FLASH irradiation method, when the dose rate of radiation from the radiation generator 412 is significantly below a set value, the control function 435a controls so as to increase the output by the radiation generator 412.

[0066] In this way, the control function 435a monitors the radiation dose in real time, and controls the radiation dose to be increased if the dose rate condition in the FLASH irradiation method is not satisfied (if the dose rate is lower than the setting). In the FLASH irradiation method, the advantage of irradiating a high dose of radiation is that the effect of radiation therapy on the target tissue is not changed, and the occurrence of damage in normal tissue is suppressed. Therefore, by the control function 435a controlling the radiation dose to be increased if the dose rate condition is not satisfied, it is possible to ensure higher safety and effectiveness in the irradiation of radiation by the FLASH irradiation method.

[0067] An example of processing by the radiotherapy apparatus 400 will be described below with reference to Fig. 5. Fig. 5 is a flowchart showing a processing procedure by the radiotherapy apparatus 400 according to the first embodiment. Here, steps S101 and S103 to S106 in Fig. 5 are realized, for example, by the processing circuitry 435 reading out a program corresponding to the control function 435a from the storage circuitry 434 and executing the program. Also, step S102 is realized, for example, by the processing circuitry 435 reading out a program corresponding to the acquisition function 435b from the storage circuitry 434 and executing the program.

[0068] In the radiotherapy apparatus 400 according to the first embodiment, as shown in FIG. 5, the processing circuitry 435 starts irradiation of radiation (step S101) and acquires dose information from the dosimeter 413 (step S102).

[0069] Then, the processing circuit 435 calculates the cumulative dose and the dose rate (step S103), predicts the remaining irradiation information (step S104), and determines whether or not the predicted dose (provisional target dose) taking into account the response time has been reached (step S105).

[0070] Here, if the predicted dose considering the response time has not been reached (step S105, No), the processing circuitry 435 returns to step S102 and acquires dose information. On the other hand, if the predicted dose considering the response time has been reached (step S105, Yes), the processing circuitry 435 stops the irradiation of radiation (step S106).

[0071] As described above, according to the first embodiment, the radiation generator 412 irradiates radiation. The dosimeter 413 measures the dose of radiation irradiated from the radiation generator 412 over time. The control function 435a controls the irradiation of radiation until a target dose is reached based on the dose of radiation measured over time. Therefore, the radiation therapy device 400 according to the first embodiment can monitor the dose of radiation in real time and control the stop of radiation, making it possible to improve the accuracy of the irradiation dose. In addition, the radiation therapy device 400 according to the first embodiment can monitor the dose of radiation in real time and control the irradiation of radiation until a target dose is reached, making it possible to improve the accuracy of the irradiation dose.

[0072] Furthermore, according to the first embodiment, the control function 435a calculates the accumulated dose and dose rate of radiation irradiated from the radiation generator 412 based on the dose of radiation measured over time, and controls the dose rate of radiation irradiated until a target dose is reached based on the accumulated dose and dose rate. Therefore, the radiation therapy apparatus 400 according to the first embodiment can perform control according to the dose rate conditions, and enables radiation irradiation by the FLASH irradiation method to be performed while ensuring high safety and effectiveness.

[0073] According to the first embodiment, the control function 435a controls the radiation generator 412 to stop radiation or change the radiation dose based on the accumulated dose and the dose rate. Therefore, the radiation therapy apparatus 400 according to the first embodiment makes it possible to perform control according to the situation in radiation irradiation by the FLASH irradiation method.

[0074] According to the first embodiment, the control function 435a predicts remaining irradiation information indicating at least one of a remaining irradiation dose, which is the remaining irradiation dose until the target dose is reached, and a remaining irradiation time, which is the time until the target dose is reached, from the accumulated dose of radiation and the dose rate, and controls the radiation generator 412 to stop irradiation of radiation based on the prediction result. Therefore, the radiation therapy apparatus 400 according to the first embodiment makes it possible to perform radiation irradiation with high accuracy with respect to the target dose.

[0075] According to the first embodiment, the control function 435a predicts the remaining irradiation information based on the dose of radiation irradiated during the response time from the time when an irradiation stop command to stop irradiation of radiation is issued until the radiation is stopped, the accumulated dose, and the dose rate. Therefore, the radiotherapy device 400 according to the first embodiment can irradiate radiation taking the response time into consideration, and can further improve the accuracy of the irradiation dose.

[0076] According to the first embodiment, the control function 435a predicts the remaining irradiation information using the radiation dose measured after a predetermined period has elapsed since the start of irradiation. Therefore, the radiotherapy device 400 according to the first embodiment can calculate the remaining irradiation information in a stable output state, and can predict the remaining irradiation information with high accuracy.

[0077] Moreover, according to the first embodiment, the control function 435a controls the radiation generator 412 to stop irradiation of radiation when the dose rate based on the dose measured by the dosimeter 413 falls below a threshold. Therefore, the radiation therapy device 400 according to the first embodiment makes it possible to appropriately perform radiation irradiation by the FLASH irradiation method. Specifically, the radiation therapy device 400 according to the first embodiment makes it possible to ensure higher safety and effectiveness in irradiation of radiation by the FLASH irradiation method by controlling to stop irradiation of radiation by the FLASH irradiation method when the dose rate condition is not satisfied.

[0078] According to the first embodiment, the control function 435a controls the radiation generator 412 to increase the radiation dose when the dose rate based on the dose measured by the dosimeter 413 falls below a threshold. Therefore, the radiation therapy device 400 according to the first embodiment makes it possible to appropriately perform radiation irradiation by the FLASH irradiation method. Specifically, the radiation therapy device 400 according to the first embodiment controls to increase the radiation dose when the dose rate condition is not satisfied, thereby making it possible to maintain a high dose in radiation irradiation by the FLASH irradiation method, and to maintain a state in which the effect on the target tissue is high and the influence on normal tissue is low, thereby ensuring higher safety and effectiveness.

[0079] Second Embodiment In the above-described embodiment, a case where radiation irradiation up to a target dose is performed in a single irradiation has been described. In the second embodiment, a case where radiation irradiation up to a target dose is performed by dividing the irradiation into a plurality of separate irradiations will be described. For example, when monitoring the radiation dose, if real-time performance is low (e.g., if the responsiveness of the dosimeter 413 is low), there is a risk that the target dose and the actual accumulated dose will differ significantly if radiation irradiation up to a target dose is performed in a single irradiation.

[0080] Therefore, in the radiotherapy device 400 according to the second embodiment, radiation irradiation is divided into multiple fractional irradiations, and the conditions for subsequent fractional irradiations are changed based on the results of each fractional irradiation, thereby improving the accuracy of the irradiation dose. The radiotherapy device 400 according to the second embodiment is different from the first embodiment in the control by the control function 435a. This will be mainly described below.

[0081] The control function 435a according to the second embodiment controls fractional irradiation at fractional target irradiation doses obtained by dividing a target irradiation dose (target dose), and adjusts the fractional target irradiation dose for each fractional irradiation according to the irradiation dose in the fractional irradiation that has already been performed. Specifically, the control function 435a performs radiation irradiation by a plurality of fractional irradiations, and adjusts the target dose in the subsequent fractional irradiation based on the cumulative dose in each fractional irradiation.

[0082] FIG. 6 is a diagram for explaining the control by the control function 435a according to the second embodiment. Here, in FIG. 6, the total dose (accumulated dose) of radiation irradiated to the irradiation area is shown on the vertical axis, and the irradiation time is shown on the horizontal axis. Also, in FIG. 6, the value of the accumulated dose calculated based on the dose measured by the dosimeter 413 is plotted with black circles. Note that in FIG. 6, the intervals between the plotted black circles are shown widely for the sake of convenience of explanation, but in reality, the dose is measured more frequently. Also, FIG. 6 shows a case where the radiation irradiation for irradiating the target dose "a" is divided into four.

[0083] For example, the control function 435a sets a divided target dose "a / 4" by dividing the radiation irradiation for irradiating the target dose "a" into four, as shown in Fig. 6. Then, the control function 435a executes the divided irradiation for the divided target dose "a / 4". For example, the control function 435a calculates an integrated dose over time based on the dose measured during radiation irradiation, as shown in the graph on the left side of Fig. 6.

[0084] Here, if the real-time performance is low due to the responsiveness of the dosimeter 413, a discrepancy occurs between the time when the accumulated dose is calculated and the accumulated dose actually being irradiated. Therefore, the control function 435a determines whether the accumulated dose calculated based on the dose measured during irradiation of radiation is close to the divided target dose "a / 4", and performs control to stop irradiation of radiation when it is close.

[0085] Then, the control function 435a calculates the cumulative dose of the actually irradiated radiation based on the dose finally measured by the dosimeter 413, and adjusts the fractional target dose of the next fractional irradiation based on the calculation result. For example, as shown in the graph on the left side of Fig. 6, when the cumulative dose of the actually irradiated radiation does not reach the fractional target dose "a / 4", the control function 435a adjusts the fractional target dose to "a / 4+α" by adding the shortfall, and executes the next fractional irradiation.

[0086] Similarly, for the next fractional irradiation, the control function 435a calculates the accumulated dose of radiation actually irradiated based on the dose finally measured by the dosimeter 413, and adjusts the fractional target dose of the next fractional irradiation based on the calculation result. For example, as shown in the second graph from the left in Fig. 6, the control function 435a calculates the accumulated dose of radiation actually irradiated, compares the accumulated dose obtained by adding up the accumulated dose in the first fractional irradiation and the accumulated dose in the second fractional irradiation with the fractional target dose for two irradiations, "a / 2", and adjusts the fractional target dose in the third fractional irradiation.

[0087] As an example, the control function 435a compares the sum of the accumulated dose in the first fractional irradiation that has not reached the fractional target dose "a / 4" and the accumulated dose in the second fractional irradiation that has exceeded the fractional target dose "a / 4+α" with the fractional target dose for two irradiations, "a / 2," and sets the fractional target dose "a / 4-β" for the third fractional irradiation.

[0088] In this way, the control function 435a according to the second embodiment divides radiation irradiation into a plurality of fractional irradiations, and adjusts the target dose in the subsequent fractional irradiations based on the integrated dose in each fractional irradiation.

[0089] An example of processing by the radiotherapy apparatus 400 will be described below with reference to Fig. 7. Fig. 7 is a flowchart showing a processing procedure by the radiotherapy apparatus 400 according to the second embodiment. Here, steps S201, S202, and S204 to S210 in Fig. 2 are realized, for example, by the processing circuitry 435 reading out a program corresponding to the control function 435a from the storage circuitry 434 and executing the program. Also, step S203 is realized, for example, by the processing circuitry 435 reading out a program corresponding to the acquisition function 435b from the storage circuitry 434 and executing the program.

[0090] 7, in the radiotherapy apparatus 400 according to the second embodiment, the processing circuitry 435 sets a fractional target dose (step S201) and starts irradiation of radiation by fractional irradiation (step S202). Then, the processing circuitry 435 acquires dose information from the dosimeter 413 (step S203), calculates an accumulated dose and a dose rate (step S204), and determines whether the accumulated dose is close to the fractional target dose (step S205).

[0091] Here, if the accumulated dose is not close to the fractional target dose (step S205, negative), the processing circuitry 435 returns to step S203 and acquires dose information. On the other hand, if the accumulated dose is close to the fractional target dose (step S205, positive), the processing circuitry 435 calculates the difference between the actual accumulated dose and the fractional target dose (step S206) and determines whether all fractional irradiations have been completed (step S207).

[0092] Here, if all fractional irradiations have not been completed (step S207, negative), the processing circuitry 435 adjusts the fractional target dose based on the calculated difference (step S208), returns to step S202, and starts irradiation of radiation. On the other hand, if all fractional irradiations have been completed (step S207, positive), the processing circuitry 435 calculates the difference between the integrated dose and the target dose in all fractional irradiations (step S209), stores the irradiation history, and ends irradiation of radiation (step S210).

[0093] As described above, according to the second embodiment, the control function 435a controls the fractional irradiation at the fractional target irradiation dose obtained by dividing the target irradiation dose, and adjusts the fractional irradiation dose for each fractional irradiation according to the irradiation dose in the fractional irradiation that has already been performed. Therefore, the radiotherapy device 400 according to the second embodiment makes it possible to improve the accuracy of the irradiation dose even when the real-time property is low.

[0094] (Other embodiments) Although the first and second embodiments have been described above, the present invention may be embodied in various different forms other than the above-described first and second embodiments.

[0095] In the above-described embodiment, the case where the remaining irradiation information is calculated from the accumulated dose and the dose rate based on the dose measured by the dosimeter 413 has been described. However, the embodiment is not limited to this, and for example, the remaining irradiation information may be predicted using artificial intelligence (AI). In such a case, for example, a trained model that has learned the relationship between the temperature and humidity and the dose rate may be used. That is, a trained model that uses the temperature and humidity and the dose rate as input data and outputs the dose rate after fluctuation is generated in advance, and the control function 435a predicts the dose rate after fluctuation using the trained model.

[0096] FIG. 8 is a diagram for explaining an example of processing by the control function 435a according to another embodiment. For example, the control function 435a first calculates a dose rate based on a dose measured by a dosimeter. Then, as shown in FIG. 8, the control function 435a inputs the current temperature, the current humidity, and the dose rate based on the dose measured by the dosimeter into the trained model to obtain a dose rate after the change. Furthermore, the control function 435a predicts the remaining irradiation information using the dose rate after the change. Note that the trained model shown in FIG. 8 is generated in advance by learning the relationship between the temperature, humidity, dose rate, and the dose rate after the change, and is stored in the storage circuitry 434.

[0097] In the above-described embodiment, each processing function of the processing circuitry 435 has been described. Here, for example, each of the above-described processing functions is stored in the storage circuitry 434 in the form of a program executable by a computer. The processing circuitry 435 realizes the processing function corresponding to each program by reading each program from the storage circuitry 434 and executing the read program. In other words, the processing circuitry 435 in a state in which each program has been read has each processing function shown in FIG. 3.

[0098] 3, an example in which each processing function is realized by a single processing circuit 435 has been described, but the embodiment is not limited to this. For example, the processing circuit 435 may be configured by combining multiple independent processors, and each processor may execute a program to realize each processing function. Furthermore, each processing function of the processing circuit 435 may be appropriately distributed or integrated and realized in a single or multiple processing circuits.

[0099] The term "processor" used in the description of each of the above-mentioned embodiments means, for example, a circuit such as a central processing unit (CPU), a graphics processing unit (GPU), an application specific integrated circuit (ASIC), a programmable logic device (for example, a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA)). Here, instead of storing a program in a memory circuit, the program may be directly built into the circuit of the processor. In this case, the processor realizes its function by reading and executing the program built into the circuit. Furthermore, each processor in the present embodiment is not limited to being configured as a single circuit for each processor, and may be configured as a single processor by combining multiple independent circuits to realize its function.

[0100] Here, the program executed by the processor is provided in advance in a ROM (Read Only Memory) or a storage unit. The program may be provided in a computer-readable storage medium such as a CD (Compact Disk)-ROM, a FD (Flexible Disk), a CD-R (Recordable), or a DVD (Digital Versatile Disk) in a format that can be installed in these devices or in a format that can be executed. The program may be provided or distributed by being stored on a computer connected to a network such as the Internet and downloaded via the network. For example, the program is composed of modules including each functional unit. As actual hardware, a CPU reads out the program from a storage medium such as a ROM and executes it, so that each module is loaded onto a main storage device and generated on the main storage device.

[0101] According to at least one of the embodiments described above, the accuracy of the irradiation dose can be improved.

[0102] Although some embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations of embodiments can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents as described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0103] 400 Radiation therapy equipment 412 Radiation Generator 413 Dosimeter 435a Control Functions

Claims

1. an irradiation unit that irradiates radiation; a measuring unit that measures a dose of radiation irradiated from the irradiating unit over time; a control unit that calculates a dose rate from a current measurement result and a measurement result immediately before each measurement of the radiation dose, calculates a dose of radiation to be irradiated during a response time from a point in time when an irradiation stop command to stop the irradiation of the radiation is issued until the radiation is stopped using the calculated dose rate, calculates a remaining irradiation time until the radiation is stopped based on the calculated dose, an integrated dose at the current time, and the current dose rate, and stops the irradiation of the radiation when the calculated remaining irradiation time becomes zero; A radiation therapy device comprising:

2. The radiotherapy apparatus according to claim 1 , wherein the control unit controls a dose rate of the radiation based on the current accumulated dose and the current dose rate.

3. The radiotherapy apparatus according to claim 2 , wherein the control unit controls the irradiation unit so as to change a dose rate of the radiation based on the current accumulated dose and the current dose rate.

4. The radiation therapy device according to any one of claims 1 to 3, wherein the control unit calculates the remaining irradiation time using a dose of the radiation measured after a predetermined period has elapsed since the start of irradiation of the radiation.

5. The radiotherapy apparatus according to claim 3 , wherein the control unit controls the irradiation unit to stop irradiating the radiation when a dose rate based on the dose measured by the measurement unit falls below a threshold value.

6. The radiotherapy apparatus according to claim 3 , wherein the control unit controls the irradiator to increase the dose of the radiation when a dose rate based on the dose measured by the measuring unit falls below a threshold value.

7. The control unit controls fractionated irradiation at a fractionated target irradiation dose obtained by dividing a target dose, and adjusts the fractionated target irradiation dose for each fractionated irradiation according to the irradiation dose in the fractionated irradiation that has already been performed. The radiotherapy device according to any one of claims 1 to 3.

8. A method for operating a radiation therapy device including an irradiation unit that irradiates radiation, comprising: The radiotherapy apparatus further includes a measurement unit and a control unit. a step of measuring a dose of the irradiated radiation over time by the measurement unit; the control unit calculates a dose rate from a current measurement result and a measurement result immediately before each measurement of the dose of the radiation, calculates the dose of radiation to be irradiated during a response time from a point in time when an irradiation stop command to stop the irradiation of the radiation is issued until the radiation is stopped using the calculated dose rate, calculates a remaining irradiation time until the radiation is stopped based on the calculated dose, an integrated dose at the current time, and the current dose rate, and issues an irradiation stop command to stop the irradiation of the radiation when the calculated remaining irradiation time becomes zero; A method comprising:

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