Radiation irradiation system, radiation therapy system, and radiation irradiation method

Abstract

To provide a system and a method that enable irradiation of radiation of different intensities at low costs and with high reliability.SOLUTION: A radiation irradiation system 106 for irradiating an irradiation target with radiation 103 of different intensities, includes: radiation monitoring units 202, 206 that detect radiation and acquire radiation information; a monitor control unit 209 that changes a value of a parameter when the radiation information is detected, according to an intensity of radiation; and a determination unit that determines whether a change of the value of the parameter by the monitor control unit is correct.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a radiation irradiation system, a radiation therapy system, and a radiation irradiation method. [Background technology]

[0002] Radiation therapy is a treatment that aims to eradicate tumors and relieve pain by irradiating tumors in the patient's body with radiation such as X-rays, electron beams, proton beams, and heavy particle beams. In general, radiation therapy involves accelerating radiation (hereafter referred to as beam) in an accelerator system consisting of a linear accelerator or synchrotron, transporting it to an irradiation nozzle, and irradiating the tumor. There are two main beam irradiation methods: passive and scanning. In the passive method, the beam is expanded using scatterers and collimators to match the shape of the tumor. On the other hand, the scanning method is a method in which the direction of a thin beam called a pencil beam is adjusted by a scanning magnet to sequentially irradiate the entire tumor. In both irradiation methods, the irradiation dose is monitored by a dose monitor on the beam path. The irradiation control device calculates the cumulative dose from the measured value of the dose monitor, and when it is confirmed that the target irradiation dose included in the irradiation instruction data (hereafter referred to as prescription) created in advance by the treatment planning device has been reached, it instructs the transition to the next irradiation or the completion of irradiation. Therefore, in order to improve the accuracy of the dose distribution and thus the therapeutic effect, a high measurement accuracy is required for the dose monitor.

[0003] Ionization chambers are widely used for dose monitors. An ionization chamber is a container in which the gap between two or more electrodes is filled with a fluid such as a gas or liquid. When radiation is incident, positive ions and electrons are generated along the trajectory of the radiation by ionization of the fluid. By applying a voltage between the electrodes, the positive ions and electrons move to the opposite electrodes, respectively, and a current flows for a short period of time. By measuring this current, for example by converting it into a voltage, the number of ionization reactions and, therefore, the dose can be calculated. Since the intensity of the pulse current is roughly proportional to the dose rate of the irradiation beam, an appropriate current-voltage conversion coefficient is set using an analog circuit, etc., taking into account the range of beam dose rates used in treatment and the input voltage capacity of the signal processing system.

[0004] In recent years, ultra-high dose rate radiation therapy, or FLASH therapy, has been attracting attention, and the demand for irradiation at higher dose rates than before is increasing. FLASH therapy requires a dose rate of approximately 40 Gy / s or more, compared to the conventional dose rate of about 1 Gy / min. Therefore, since there is a difference of about 1000 times between the conventional dose rate and the dose rate suitable for FLASH, a radiation therapy system compatible with both conventional therapy and FLASH therapy is required to irradiate with high precision within the wide range of dose rates specified.

[0005] Patent Document 1 discloses a method for monitoring and controlling the irradiation dose with high accuracy regardless of the dose rate by connecting multiple systems of current-voltage conversion amplifiers and downstream pulse counters in a dose monitor signal processing system and selecting the system to be used for dose monitoring and control based on dose rate information included in the treatment plan. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2016-154630 A Summary of the Invention [Problem to be solved by the invention]

[0007] In Patent Document 1, it is necessary to connect a plurality of signal processing systems for the dose monitor, which increases the device cost and the operating cost.

[0008] The present disclosure has been made in consideration of the above circumstances, and discloses a radiation therapy system that enables low-cost, highly accurate beam monitoring at both conventional dose rates and FLASH dose rates by safely switching to monitor system parameters suitable for the irradiation dose rate based on the treatment plan.

[0009] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a radiation irradiation system, a radiation therapy system, and a radiation irradiation method that are capable of irradiating radiation of different intensities at low cost and with high reliability. [Means for solving the problem]

[0010] In order to solve the above problems, a radiation irradiation system according to the present disclosure is a radiation irradiation system that irradiates an irradiation target with radiation of different intensities, and includes a radiation monitor unit that detects radiation and acquires radiation information, a monitor control unit that changes parameter values ​​when the radiation information is detected in accordance with the intensity of the radiation, and a judgment unit that judges whether the change in parameter value made by the monitor control unit is correct. Effect of the Invention

[0011] According to the present invention, by changing the parameter values ​​of the radiation monitor unit, it is possible to obtain radiation information of radiation of different intensities, and further to determine whether the change in the parameter value is correct. [Brief description of the drawings]

[0012] [Figure 1] 1 is an overall configuration diagram of a radiation therapy system including a radiation irradiation system. [Diagram 2] FIG. 2 is a diagram showing a configuration of an irradiation nozzle. [Diagram 3] FIG. 2 is a diagram illustrating an example of a configuration of a dose monitor. [Figure 4] 1 is a flowchart of radiation therapy. [Diagram 5] FIG. 13 is a diagram showing a method for determining whether to switch settings of a dose monitor. [Figure 6] 13 is a diagram showing an example of a circuit configuration for determining whether the switching of the setting of the dose monitor is normal. [Figure 7] 11 shows another example of a circuit configuration for determining whether the switching of the setting of the dose monitor is normal or not according to the second embodiment. [Figure 8] FIG. 11 is a diagram illustrating a configuration of an irradiation nozzle according to a third embodiment. [Figure 9] 11 is a flowchart of radiation therapy according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the radiation irradiation system according to this embodiment, a signal processing system that processes signals output by a dose monitor is integrated, and the circuit parameter values ​​are switched according to the dose rate, thereby reducing costs. However, in order to maintain high reliability, it is not enough to simply switch the parameter values ​​of the dose monitor system; it is also necessary to check whether the parameter values ​​are set correctly.

[0014] For example, when the difference between parameters is about 1000 times, as in the case of FLASH therapy, there is concern about incorrect irradiation due to malfunction of switching and the impact on the signal processing system. For example, if the value of the coefficient for converting current to voltage is set too small, the signal size will be smaller than the noise, so the value when the beam is irradiated and the value when the beam is stopped may become close. Conversely, if the value of the coefficient for converting current to voltage is set too large, the beam will stop at about 1 / 1000 of the prescribed dose.

[0015] Therefore, in order to perform a combination of FLASH therapy and conventional therapy with high accuracy and appropriateness, it is desirable to switch the dose monitor system parameter values ​​according to the dose rate and to verify the validity of the switch between the time of switching and the start of irradiation.

[0016] Therefore, the radiation irradiation system disclosed herein can safely switch to monitor system parameter values ​​appropriate for the irradiation dose rate based on the treatment plan, thereby enabling beam monitoring at low cost and with high accuracy regardless of whether the dose rate is conventional or for FLASH, thereby achieving highly reliable beam irradiation. EXAMPLES

[0017] A radiotherapy system 101 according to a first embodiment will be described with reference to Figs. 1 to 6. In this embodiment, radiotherapy is performed using a scanning method. The radiotherapy system 101 is assumed to be a radiotherapy system that uses a proton beam or a heavy particle beam as a beam, but may be a scanning method that uses other radiation such as X-rays.

[0018] First, the overall configuration of a radiation therapy system 101 will be described with reference to Fig. 1. Fig. 1 is a diagram showing the overall configuration of the radiation therapy system 101.

[0019] The radiation therapy system 101 is a system that treats an irradiation target 102 by irradiating the target with a beam 103. The radiation therapy system 101 includes, for example, an accelerator system 104, a beam transport system 105, an irradiation nozzle 106, a treatment table 107, an overall control device 108, an accelerator / beam transport system control device 109, an irradiation control device 110, and a treatment planning device 111.

[0020] The accelerator system 104 is a device that generates and accelerates the beam 103. Although an example of an accelerator including the injector 112, the synchrotron accelerator 113, and the ion source 114 is shown in Fig. 1, the accelerator system is not limited to this, and may be, for example, another device group that accelerates a particle beam, such as a cyclotron accelerator or a linear accelerator.

[0021] The beam transport system 105 is a group of devices that transport the beam to the irradiation nozzle 106. The irradiation nozzle 106, which is an example of a "radiation irradiation system", irradiates the irradiation target 102 with the beam 103. The beam transport system 105 transports the beam 103 accelerated by the accelerator 104 to the irradiation nozzle 106, and connects the accelerator 104 and the irradiation nozzle 106. The beam transport system 105 in this embodiment has a rotating gantry. A fixed irradiation port may be used instead of the rotating gantry. The beam transport system 105 may be omitted, and the accelerator system 104 may be directly connected to the irradiation nozzle 106.

[0022] The irradiation nozzle 106 adjusts the beam 103 transported from the beam transport system 105 and irradiates the irradiation target 102 with the beam. The irradiation nozzle 106 further includes a group of devices that measure the characteristics of the irradiated beam 103. The irradiation nozzle 106 will be described in detail later with reference to FIG. 2.

[0023] The treatment planning device 111 is configured as a computer system having, for example, an arithmetic unit, a memory, a storage device, a communication interface device, a user interface device (none of which are shown), etc. The treatment planning device 111 executes a treatment plan created by a doctor or the like to create a prescription, and transfers the prescription to the overall control device 108. The created prescription includes information on the beam current for each irradiation unit.

[0024] The overall control device 108 is connected to a treatment planning device 111, an accelerator / beam transport system control device 109, an irradiation control device 110, and a treatment table 107, and controls the operation of each piece of equipment based on the prescription transferred from the treatment planning device 111.

[0025] The accelerator / beam transport system controller 109 controls the operation of each device constituting the accelerator system 104 and the beam transport system 105 based on instructions from the overall controller 108.

[0026] The irradiation controller 110 controls the operation of each device constituting the irradiation nozzle 106 based on instructions from the overall controller 108. The irradiation controller 110 processes measurement results transmitted from each monitor of the irradiation nozzle 106, and transfers them to the overall controller 108. The detailed configuration of the irradiation controller 110 will be described later with reference to FIG. 6.

[0027] The overall controller 108, the accelerator / beam transport system controller 109, and the irradiation controller 110 each have a CPU and a memory connected to the CPU.

[0028] The control process for the operations to be executed may be integrated into one program, or may be divided into multiple programs, or may be a combination of these.

[0029] Some or all of the programs held by each device may be implemented by dedicated hardware or may be modularized. Furthermore, the various programs may be installed in each device by a program distribution server or an external storage medium.

[0030] Each device may be an independent device and connected to a wired or wireless network, or a plurality of devices may be integrated into one device.

[0031] The treatment table 107 is a bed on which the irradiation target 102 is placed. The treatment table 107 is movable in so-called six-axis directions. Based on instructions from the overall control device 108, the treatment table 107 can move in three orthogonal axial directions and can also rotate around each axis. By these movements and rotations, the treatment table 107 can move the irradiation target 102 to a desired position.

[0032] The accelerator / beam transport system controller 109 is a device that controls the accelerator 104 and the beam transport system 105 .

[0033] A detailed configuration of the irradiation nozzle 106 will be described with reference to Fig. 2. Fig. 2 shows an example of the irradiation nozzle 106 that irradiates a beam by a scanning method.

[0034] For example, a plurality of scanning electromagnets 201A and 201B, a dose monitor 202, and a position monitor 203 are arranged in the irradiation nozzle 106. Furthermore, the irradiation nozzle 106 may be provided with a ridge filter 204 and a range shifter 205 as necessary.

[0035] The irradiation nozzle 106 further includes a dose monitor signal processing system 206 , a position monitor signal processing system 207 , a scanning magnet control device 208 , and a monitor setting control device 209 .

[0036] The irradiation controller 110 is connected to a dose monitor signal processing system 206 , a position monitor signal processing system 207 , a scanning magnet controller 208 , and a monitor setting controller 209 .

[0037] The scanning magnets 201A and 201B deflect the beam 103 by the generated magnetic field. The scanning magnets 201A and 201B deflect the beam in directions perpendicular to each other. As a result, the beam 103 is scanned in two dimensions and irradiated to a target volume 210 in the irradiation subject 102. In the case of treating a cancer patient, the irradiation subject 102 represents the patient, and the target volume 210 represents an area including the tumor plus a margin (a margin area that takes into account an error in the irradiation position).

[0038] The ridge filter 204 is used to expand the dose distribution in the incident direction. The range shifter 205 is used to adjust the penetration depth of the beam 103.

[0039] The dose monitor 202 is a monitor for measuring the dose rate and thus the dose of the irradiated beam 103. The dose monitor 202 transmits a dose monitor output having a magnitude corresponding to the dose rate to a dose monitor signal processing system 206.

[0040] In this embodiment, for example, an ionization chamber is used as the dose monitor 202. In this case, the dose monitor output corresponds to the collected current of the ionization chamber. The dose monitor 202 may be another type of monitor having a correlation between the dose rate of the beam and the detection signal, such as a phosphor or semiconductor detector. The dose monitor signal processing system 206 processes the dose monitor output input from the dose monitor 202 and outputs it to the irradiation controller 110 as a dose signal. The irradiation controller 110 calculates the irradiated dose based on the dose signal input from the dose monitor signal processing system 206. The dose monitor signal processing system 206 may also be called a dose monitor signal processor 206.

[0041] The position monitor 203 is a monitor for measuring the position and size of the irradiated beam 103. The output of the position monitor 203 is input to a position monitor signal processing system 207. In this embodiment, a multi-wire ionization chamber is used as the position monitor 203. In this case, the position monitor output corresponds to a set of collected current values ​​output from each wire of the ionization chamber. The position monitor 203 may be another type of monitor that outputs a group of detection signals that are correlated with the dose rate of the beam at each point in a two-dimensional plane, such as a multi-strip ionization chamber or a two-dimensional array phosphor detector.

[0042] The position monitor signal processing system 207 processes the position monitor output and outputs it as a position / size signal to the irradiation controller 110. The position / size signal is a signal that indicates the position and size of the beam.

[0043] The irradiation controller 110 calculates the position and size of the irradiated beam based on the position / size signal input from the position monitor signal processing system 207. The position monitor signal processing system 207 can also be called a position monitor signal processing unit 207.

[0044] The monitor setting control device 209 is connected to either or both of the dose monitor signal processing system 207 and the position monitor signal processing system 208, and sends an instruction to switch the parameters (hereinafter referred to as monitor settings) of the connected monitor signal processing system.

[0045] FIG. 3 shows an example of the circuit of the dose monitor signal processing system 206.

[0046] Here, the dose monitor 202 and the dose monitor signal processing system 206 are examples of a "radiation monitor unit." The dose monitor 202 is an example of a "sensor unit." The dose monitor signal processing system 206 is an example of a "signal processing circuit." The dose or dose rate is an example of "radiation information." The monitor setting control device 209 is an example of a "monitor control unit." The "judgment unit" is, for example, steps S111 and S112, or one of steps S111 and S112, in FIG. 4 described later. Furthermore, the "judgment unit" may also include step S113. The overall control unit 108 may be an example of a "judgment unit" and / or a "monitor control unit."

[0047] The collected current output from the ionization chamber-type dose monitor 202 is input to a downstream current-voltage conversion circuit 301, which converts it into a voltage signal. The voltage signal is converted into a frequency signal by a voltage-frequency converter 302, and transmitted to the irradiation controller 110 as a dose monitor signal. The voltage-frequency converter 302 is a circuit that converts a voltage signal into a frequency signal, and is indicated as a "VF converter" in the figure. The resistance value of the current-voltage conversion circuit 301 can be switched to one of a plurality of resistance values ​​by a switch 303. The switch 303 is controlled by the monitor setting control device 209. Here, there are two parallel circuits (referred to as a first parallel circuit and a second parallel circuit). The first parallel circuit has a resistance value R1. The second parallel circuit has a resistance value R2.

[0048] For example, if the relationship is R1 = R2 × 1000, the output voltage when switching to the second parallel circuit will be 1 / 1000 of the output voltage of the first parallel circuit. Therefore, even if there is a 1000-fold difference in beam intensity between conventional therapy and ultra-high dose rate therapy, it is possible to obtain the same voltage output by switching between the two parallel circuits, and the signal will not saturate or the signal-to-noise ratio will not decrease.

[0049] In Fig. 3, the resistance value of the current-voltage conversion circuit 301 is assumed as the monitor setting. In Fig. 3, two parallel circuits, a first parallel circuit having a resistance value R1 and a second parallel circuit having a resistance value R2, are illustrated as an example, but the present invention is not limited to this, and three or more parallel circuits may be used. A fixed resistor with a fixed resistance value may be used, or a variable resistor whose resistance value can be changed continuously or stepwise may be used.

[0050] The conversion coefficient of the voltage frequency converter 302 may be changed via the monitor setting control device 209. The circuit configuration of the signal processing system 206 is not limited to the above, and may include, for example, a capacitor or other amplifier circuit.

[0051] By using different signal conversion circuitry, signals other than frequency signals may be transmitted to the irradiation controller 110 .

[0052] This concludes the detailed description of the configuration of the radiation therapy system 101 and each device. Hereinafter, the operation procedure of the system in the first embodiment will be described.

[0053] The treatment procedure by the radiation treatment system 101 will be described with reference to Fig. 4. Fig. 4 is a flowchart of the radiation treatment.

[0054] In general, in radiation therapy, fractionated irradiation is performed in which the target dose is divided into several doses. This is to prevent normal tissue from being damaged by a high dose being given at once. In this embodiment, a treatment period is assumed to be divided into 30 days, for example, and the target dose is irradiated, but the number of fractions and the amount of irradiation are not particularly important. The fraction unit does not have to be one day, and one day of treatment may be divided into multiple sessions.

[0055] When treatment for each day is started (S101), first, the treatment planning device 111 executes a treatment plan (S102). The detailed procedure of the treatment plan is as follows.

[0056] The treatment planning device 111 reads in-vivo images of the patient's affected area and the surroundings captured by X-ray CT or the like. Next, based on the in-vivo images displayed on the user interface device, the doctor extracts the contours of the tumor and risk organs, and adds a predetermined margin to these contours to determine the target volume 210 and the contours of the risk organs.

[0057] The treatment planning device 111 creates a prescription. First, the treatment planning device 111 sets a target dose and a target beam intensity index for the target volume 210 and the organs at risk. The beam intensity index represents an arbitrary index that depends on the beam intensity and is determined for each minute region in the patient's body, and may be, for example, an average dose rate obtained by dividing the dose by the time required for irradiation.

[0058] The target dose and the target beam intensity index are input by the doctor via the user interface device. The treatment planning device 111 performs irradiation optimization calculations to give the target dose and the target beam intensity index and determines a prescription.

[0059] The prescription specifies the irradiation position, irradiation amount, irradiation intensity, irradiation direction, and irradiation sequence of each pencil beam. The dose distribution and beam intensity index distribution formed by the prescription are presented to the doctor via the user interface device. The prescription approved by the doctor is sent to the overall control device 108. The overall controller 108 creates control instruction data for each irradiation group based on the prescription received from the treatment planning device 111, and transmits it to the accelerator / beam controller 109 and the irradiation controller 110. The transmitted data is stored in a memory in the accelerator / beam controller 109 and a memory in the irradiation controller 110 (neither of which are shown).

[0060] The prescription is now created. If the doctor does not approve the prescription, the target dose or target beam intensity indicators are reset.

[0061] The patient is placed on the treatment couch 107. The overall control device 108 moves the treatment couch 107 to match the position of the patient when the in-vivo images are taken. Thereafter, the radiation therapy system 101 starts preparation for irradiation of the beam 103.

[0062] The irradiation for each day is divided into several irradiation groups. The boundaries of the irradiation groups are set, for example, at points where the irradiation position is significantly changed or where the irradiation direction or irradiation intensity is changed. When preparation for irradiation for the first irradiation group is started (S103), the accelerator / beam transport system control device 109 starts accelerating the beam according to the control instruction data. The irradiation control device 110 changes the current values ​​of the scanning magnets 201A and 201B by the scanning magnet control device 208 based on the irradiation position information shown in the prescription. In parallel with these preparations, the overall control device 108 judges whether or not the monitor settings are to be switched (S104).

[0063] Using FIG. 5, the procedure for determining whether or not the monitor setting has been switched will be described taking the first to third irradiation groups as an example.

[0064] The overall control device 108 stores the irradiation intensity ranges RA1 and RA2 corresponding to each monitor set value (resistance values ​​R1 and R2 of the current-voltage conversion circuit 301 in FIG. 3) as set values ​​in a memory (not shown). The range where the illuminance intensity exceeds the threshold value Th is the range RA1 where high-intensity radiation is irradiated. The range where the irradiation intensity is equal to or less than the threshold value Th is the range RA2 where low-intensity radiation is irradiated.

[0065] As shown in the lower part of FIG. 5, in the first irradiation group that is performed first, it is determined that the monitor setting needs to be changed. Since the intensity of the radiation irradiated in the first irradiation group is equal to or less than the threshold value Th, the monitor setting value is set to "2" (resistor R2 is used). When the radiation irradiation in the first irradiation group ends and irradiation in the second irradiation group starts, the radiation intensity will increase according to the treatment plan, so it is determined that the monitor setting needs to be changed. Since the intensity of the radiation irradiated in the second irradiation group exceeds the threshold value Th, the monitor setting value is set to "1" (resistor R1 is used). When the radiation irradiation in the second irradiation group ends and irradiation in the third irradiation group starts, the radiation intensity will not change according to the treatment plan. Therefore, it is determined that there is no need to change the monitor setting. The monitor setting value remains at "2".

[0066] In step S104, the overall controller 108 reads the irradiation intensity of the n-th (n=1, 2, 3) irradiation group, and calculates a monitor setting value that includes the read irradiation intensity in the irradiation intensity ranges RA1 and RA2.

[0067] If the calculated resistance value is different from the setting value at the time of irradiation of the previous irradiation group (n-1 irradiation group), it is determined that the monitor setting has been switched (S104: YES). If the setting value at the previous irradiation group and the setting value (resistance value) calculated this time match, it is determined that the monitor setting has not been switched (S104: NO). However, for the first irradiation group, it is assumed for convenience that the monitor setting has been switched.

[0068] In addition, the judgment process for each irradiation group may be executed after the start of irradiation for each irradiation group, or the switching judgment process for all irradiation groups may be executed collectively based on the treatment plan before the start of irradiation for the first irradiation group, and the judgment results may be stored in the memory of the overall control device 108.

[0069] Returning to FIG. 4, when it is determined that the monitor setting needs to be switched (S104: YES), the monitor setting is switched (S110). The overall control device 108 instructs the monitor setting control device 209 of the monitor setting to be switched and its value. The monitor setting control device 209 switches the monitor setting of the dose monitor signal processing system 206 or the position monitor signal processing system 207 based on the instruction.

[0070] Next, it is determined whether the monitor settings are correct (S111). Here, FIG. 6 is referred to. FIG. 6 is a circuit diagram in which a component for determining the monitor settings is added to the dose monitor signal processing system 206 shown in FIG. 3. A current source 401 is connected to the input side of the current-voltage conversion circuit 301. When the determination of the monitor settings is started, the current source 401 applies a specified current (test current). The magnitude of the current may be changed according to the irradiation intensity of the beam group, or may be constant regardless of the irradiation intensity. The current input from the current source 401 is converted into a voltage by the current-voltage conversion circuit 301. The value of this voltage is measured by a voltmeter 402 connected to the output side of the current-voltage conversion circuit 301.

[0071] The voltage measured by the voltmeter 402 is transmitted to the overall controller 108 via the irradiation controller 110. The overall controller 108 compares the resistance value of the current-voltage conversion circuit 301 specified as the monitor setting value with the voltage value predicted from the applied current value and the measured voltage value, and determines that the monitor setting is normal if the difference is equal to or smaller than a threshold value, and determines that the monitor setting is abnormal if the difference is greater than the threshold value (S111).

[0072] The threshold value of the voltage difference is stored in advance in a memory in the overall control device 108. The threshold value may be defined by the relative magnitude of the difference with respect to the voltage value, may be defined by the absolute magnitude of the voltage difference, or may differ for each monitor setting value.

[0073] 6 shows an example of a monitor setting determination method when the monitor setting is to switch the resistance value of the current-voltage conversion circuit 301, and other determination methods are also possible. For example, a mechanism that detects the position or operation of the switch 303 and outputs a signal may be used. When switching the setting of the voltage-frequency converter 302, the current setting value may be output as a digital signal.

[0074] Returning to Fig. 4, in step S112, it is determined whether or not the monitor settings are normal. If it is determined that the monitor settings are abnormal (S112: NO), a warning is output to the user in step S113, and the process returns to step S110. In step S110, the monitor settings are switched again.

[0075] When the monitor settings are determined to be normal (S112: YES) and the acceleration of the beam 103 and the change in the current values ​​of the scanning electromagnets 201A and 201B are also completed, irradiation of radiation and measurement of the dose are started (S105).

[0076] When the change in the current value is completed, the accelerator / beam transport system controller 109 starts the extraction of the beam. The extracted beam 103 passes through the irradiation nozzle 106 and is irradiated onto the target volume 210.

[0077] The characteristics of the irradiation beam 103 are measured by a dose monitor 202 and a position monitor 203, and the irradiation dose is integrated in the irradiation controller 110. When the irradiation dose reaches a target dose, the irradiation controller 110 transmits a completion signal to the overall controller 108 (S106). Upon receiving the completion signal, the overall controller 108 determines whether radiation irradiation for the last irradiation group of the day has been completed (S107), and if there is an irradiation group that has not been executed (S107: NO), issues an instruction to the accelerator / beam transport system controller 109 and the irradiation controller 110 (S108) to instruct them to prepare for irradiation for the second irradiation group.

[0078] The radiation therapy system 101 may be a system in which an irradiation control device 110 is connected to an accelerator / beam transport system control device 109, and signals indicating completion of acceleration and completion of irradiation are sent and received directly between the irradiation control device 110 and the accelerator / beam transport system control device 109.

[0079] The above procedure is repeated for all irradiation groups recorded in the prescription (S107: YES), and the treatment for the day is completed (S109). The same procedure is repeated until the final treatment day (S109: YES), and the particle beam therapy in this embodiment is completed. The treatment procedure by the radiation therapy system 101 is completed.

[0080] In addition, if there is no significant change in irradiation intensity during treatment and it is obvious that only the first irradiation group is judged to have had its monitor settings switched, the monitor settings may be switched and judged to be normal before starting preparation for irradiation of the first irradiation group, such as before the patient enters the room or while the patient is being fixed to the treatment table.

[0081] In the radiation therapy system 101 of this embodiment configured as described above, a part of the monitor signal processing system 206 is made switchable, and the monitor setting is switched based on the irradiation intensity specified in the treatment plan. As a result, in this embodiment, even if the beam intensity changes significantly, it is possible to maintain high dose monitoring and control accuracy. The monitor signal processing system 206 is a single system, and only a part of the circuit is changed to a switchable mechanism. Therefore, compared to the case where multiple signal processing systems are provided and measurements are performed simultaneously with different monitor setting values, the overall cost is suppressed.

[0082] Furthermore, in this embodiment, after the monitor setting is switched, the test current is actually measured to determine whether the switching is normal or abnormal, and irradiation is started only after the monitor switching setting is determined to be normal. Therefore, according to this embodiment, it is possible to avoid malfunctions in the monitor setting switching. The switching of the monitor setting and the normality determination are performed in parallel with other irradiation preparations such as beam acceleration and current changes to the deflection magnets, so that the treatment flow is not affected and the treatment time is not extended unless an abnormality is determined.

[0083] As a result, in the radiation therapy system of this embodiment, the beam can be monitored at low cost and with high accuracy in both treatments using the conventional dose rate and treatments using the high dose rate for FLASH. EXAMPLES

[0084] Second embodiment will be described with reference to Fig. 7. In the following embodiments including this embodiment, differences from the first embodiment will be mainly described.

[0085] The overall configuration of the radiation therapy system 101 in the second embodiment is the same as that in the first embodiment, but there may be differences in the configuration of the dose monitor or position monitor and the corresponding monitor signal processing system, and further in a part of the treatment flow. In this embodiment, instead of applying the test current described in the first embodiment, a test beam is irradiated to determine whether the monitor switching setting is normal or abnormal.

[0086] In this embodiment, the applied voltage of an ionization chamber type dose monitor is taken as an example of the monitor setting for switching. Fig. 7 shows a circuit diagram for determining the monitor switching setting by test irradiation of a beam.

[0087] Although not shown in Fig. 3, in the ionization chamber type dose monitor, a high-voltage power supply 501 is connected to apply a voltage between the collector electrode and the high-voltage electrode. The magnitude of the applied voltage changes the gas amplification degree, i.e., the magnitude of the collected current for the same beam intensity. Therefore, by the monitor setting control device 209 switching the applied voltage of the high-voltage power supply 501 according to the beam irradiation intensity, it is possible to obtain the same dose monitor output regardless of the irradiation intensity, even if the conversion coefficient of the current-voltage conversion circuit 502 and the voltage-to-frequency converter 503 is not variable.

[0088] However, in this embodiment, unlike the first embodiment, the settings of the dose monitor 202 itself are switched. Therefore, even if a test current is applied to the dose monitor signal processing system 206 using the configuration of Fig. 6, the state of the monitor settings cannot be actually measured. Therefore, in this embodiment, after the monitor settings are switched, a test beam irradiation is performed, and the measurement result of the dose monitor 202 is compared with a predicted value to determine whether the monitor settings have been switched normally.

[0089] The monitor setting to be switched is not limited to the applied voltage of the dose monitor 202, but may be, for example, the electrode spacing of the ionization chamber, the applied voltage of the position monitor, or the electrode spacing.

[0090] The flow of radiation therapy in this embodiment will be described below. The outline of the flow of treatment is shown in Fig. 4, similar to the embodiment 1. However, in this embodiment, after it is determined that the monitor setting needs to be switched and the monitor setting is switched, the current change of the beam acceleration and bending magnets needs to be completed by the time the monitor setting determination is started in step S111.

[0091] When the monitor setting judgment is started (S111), the overall controller 108 sends an instruction to the accelerator / beam transport system controller 109 and the irradiation controller 110 to irradiate the beam for a very short time as a test irradiation.

[0092] The micro time varies depending on the irradiation intensity of the beam group, and is stored in advance in the overall control device 108. During the micro time irradiation, it is measured by the dose monitor 202. The output of the dose monitor 202 is compared with a value predicted from the monitor setting specified at the time of switching and the micro time and irradiation intensity of irradiation, and if the difference is equal to or less than a threshold, the monitor setting is determined to be normal. If the difference is greater than the threshold, the monitor setting is determined to be abnormal.

[0093] The threshold value may be defined as a relative value of the difference with respect to the dose monitor output, or may be defined as an absolute value of the difference. The dose monitor output to be compared may be a voltage value immediately after the current-voltage conversion circuit 502, or may be the number of pulse signals immediately after the voltage-frequency converter 503. Furthermore, it may be a value obtained by integrating the above voltage value over a certain period of time.

[0094] If the monitor setting switching is performed only when the patient is not present on the treatment table 107, the patient will not be exposed to additional radiation due to the above test irradiation. On the other hand, if the monitor setting switching occurs while the patient is present on the treatment table 107, such as when the monitor setting switching is performed during treatment, the patient will be exposed to radiation due to the test irradiation. If the radiation exposure during the short time required to perform the test irradiation is sufficiently small, the irradiation may be performed according to the treatment plan after the test irradiation. If the radiation exposure due to the test irradiation cannot be ignored, the dose due to the test irradiation may be subtracted from the target dose of the therapeutic irradiation immediately after the test irradiation. The treatment flow after the monitor setting determination (S105) is the same as that of the first embodiment, and will not be described.

[0095] This embodiment configured as above also has the same effect as that of embodiment 1. Furthermore, in this embodiment, since test irradiation is performed as a monitor setting judgment, when a patient is present on the treatment table, additional processing is required, such as correcting the target dose during treatment according to the irradiation dose.

[0096] Furthermore, since the test irradiation is performed after waiting for the beam acceleration and the change in the current of the bending magnet, the treatment time is slightly longer than in the case where this embodiment is not applied. On the other hand, in this embodiment, the beam is actually irradiated and the response of the monitor system is measured, so that it is possible to verify the validity of the setting switching of the monitor body, which was not possible to judge as normal in the first embodiment. EXAMPLES

[0097] Example 3 will be described with reference to Fig. 8. In Examples 1 and 2, a radiotherapy system using the scanning method has been described as an example. In this example, a radiotherapy system or an X-ray therapy system using the passive method will be described as an example.

[0098] Most of the overall configuration of the radiation therapy system 101A is similar to that shown in FIG. 1, but in the case of the X-ray therapy system, an electron beam linear accelerator is used as the accelerator system 104, and further, a target for converting the electron beam into X-rays is installed at the most downstream of the beam transport system 105 (neither is shown).

[0099] The components of the irradiation nozzle 106A are different from those in the scanning method. Fig. 8 shows an example of the configuration of the irradiation nozzle 106A in the passive method.

[0100] The scatterer 601 is installed to expand the beam size and flatten the beam distribution. The dose monitor 602 and the dose monitor signal processing system 603 have the same configuration as in the first or second embodiment, and have the function of measuring the intensity of the passing beam. The monitor setting control device 604 issues a command to switch the monitor setting of the dose monitor 602 or the dose monitor signal processing system 603.

[0101] The multi-leaf collimator 605 is a shield in which a large number of thin metal plates are stacked in a direction perpendicular to the beam, and can form any collimator shape by independently driving each thin plate. The collimator controller 606 controls the shape of the multi-leaf collimator 605 according to instructions from the irradiation controller 110.

[0102] The ridge filter 607 and the bolus 607 are installed in the case of the radiation therapy system 101A, and change the characteristics of the beam so that the dose distribution in the depth direction matches the target volume 210. The above components form a dose distribution that dimensionally matches the target volume 210.

[0103] The prescription created by the treatment planning system 111 contains information that differs from that of the scanning method, and specifies the geometry of the multi-leaf collimator 605 for each irradiation direction, as well as the beam dose and irradiation intensity.

[0104] The configuration of the radiation therapy system 101A and the detailed description of each device are as above. The operation procedure of the system in this embodiment is generally similar to the procedure shown in the first or second embodiment. However, since there is no bending electromagnet, the shape of the multi-leaf collimator 605 is changed in the irradiation preparation in step S103. Since there is no position monitor, the monitor setting switching is applied only to the dose monitor. The present embodiment thus configured also has the same operational effects as those of embodiment 1. The present embodiment can also be applied to a radiotherapy system 101A that uses a passive method. EXAMPLES

[0105] A fourth embodiment will be described with reference to Fig. 9. In this embodiment, the results of switching monitor settings are stored and the information is provided to the user.

[0106] 9 is a flowchart of the treatment process by the radiation therapy system 101. In this embodiment, when it is determined whether the switching of the monitor settings is normal or not (S111), the history of the switching is stored in the memory of the overall control unit 108 (S114). Then, when the radiation therapy is completed (S109: YES), the overall control unit 108 creates a report 700 based on the switching history and provides it to the user (S115). The report 700 includes the history of the switching of the monitor settings corresponding to the treatment plan. A user operating the radiation therapy system 101, such as a doctor, can refer to the report 700 and utilize it in creating other treatment plans.

[0107] It should be noted that the present invention is not limited to the above-described embodiment, and includes various modified examples. The above-described embodiment has been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to the embodiment having all of the described configurations.

[0108] It is also possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment.It is also possible to add, delete, or replace part of the configuration of each embodiment with the configuration of another embodiment.

[0109] In the above embodiment, the dose monitor and the dose monitor signal processing system are switched, but the position monitor in the radiation therapy system using the scanning method often uses a principle and a signal processing method similar to those of the dose monitor. Therefore, the first and second embodiments can be applied to the setting switching and normality judgment method of the position monitor.

[0110] Furthermore, radiation therapy systems are often equipped with two monitors, a main dose monitor and a sub-dose monitor, and the above embodiment may be applied to only one of the monitors or to both monitors.

[0111] At least one of step S104 and step S111 in FIG. 4 can also be realized by machine learning.

[0112] It is apparent that the present disclosure describes the following configuration to a degree that would enable a person skilled in the art to implement it.

[0113] (Configuration 1) A radiation irradiation system that irradiates radiation of different intensities to an irradiation target, comprising: a radiation monitor unit that detects radiation and acquires radiation information; a monitor control unit that changes a parameter value when the radiation information is detected in accordance with the intensity of the radiation; and a judgment unit that judges whether the change in the parameter value made by the monitor control unit is correct.

[0114] (Configuration 2) The radiation irradiation system according to configuration 1, wherein the determining unit determines whether or not a change in a value of the parameter is correct before irradiating the irradiation target with the radiation.

[0115] (Configuration 3) The radiation irradiation system according to either of configurations 1 or 2, wherein the determination unit outputs warning information when it determines that the change in the parameter value is incorrect.

[0116] (Configuration 4) The radiation irradiation system according to any one of configurations 1 to 3, wherein the monitor control unit changes the value of the parameter according to the intensity of the radiation, based on treatment plan information for irradiating the irradiation target with radiation.

[0117] (Configuration 5) The radiation irradiating system according to any one of configurations 1 to 4, wherein the parameter is a parameter related to a signal processing circuit that detects the intensity of radiation by the radiation monitor unit.

[0118] (Configuration 6) A radiation irradiation system according to any one of configurations 1 to 5, wherein the parameter is a resistance value of a feedback resistor included in the signal processing circuit, which converts a monitor current value detected by the radiation monitor unit into a voltage value.

[0119] (Configuration 7) The radiation irradiation system of any one of configurations 1 to 6, further comprising a current source that supplies a test current to the feedback resistor, and the determination unit determines, before irradiating the irradiation target with radiation, whether a change in the value of the parameter made by the monitor control unit is correct, based on a resistance value of the feedback resistor when the test current is supplied thereto.

[0120] (Configuration 8) A radiation irradiation system according to any one of configurations 1 to 7, wherein the radiation monitor unit includes a sensor unit that detects radiation and outputs a current signal, and a signal processing circuit that processes the current signal from the sensor unit and outputs it as the radiation information, and the parameter is a parameter that changes the sensitivity of the sensor unit.

[0121] (Configuration 9) The radiation irradiation system according to any one of configurations 1 to 8, wherein the sensor unit is an ionization chamber, and the sensitivity of the sensor unit is changed by changing the value of the voltage applied between electrodes included in the ionization chamber as the parameter.

[0122] (Configuration 10) A radiation irradiation system according to any one of configurations 1 to 8, wherein the judgment unit test-irradiates radiation into a space not including the irradiation target after a parameter that changes the sensitivity of the sensor unit is changed, and judges whether the change in the parameter by the monitor unit control unit is correct.

[0123] (Configuration 11) A radiation irradiation system described in any one of configurations 1 to 4, wherein the judgment unit test-irradiates the irradiation target after a parameter that changes the sensitivity of the sensor unit is changed, and subtracts the dose of the test-irradiated radiation from the target dose described in the treatment plan.

[0124] (Configuration 12) A radiation therapy system comprising: the radiation irradiation system according to any one of configurations 1 to 11; an accelerator and a beam transport system that supply radiation of different intensities to the radiation irradiation system; and an irradiation device that irradiates the radiation supplied from the accelerator and the beam transport system to the irradiation target.

[0125] (Configuration 13) A radiation irradiation method in which radiation of different intensities is irradiated to an irradiation target by a radiation irradiation system, the radiation therapy system including a radiation monitor unit that detects radiation and acquires radiation information, changes a parameter value when the radiation information is detected according to the intensity of the radiation, and determines whether the change in the parameter value is correct. [Explanation of symbols]

[0126] 101: radiation therapy system, 102: irradiation target, 103: beam, 104: accelerator system, 105: beam transport system, 106: irradiation nozzle, 107: treatment table, 108: overall control device, 109: accelerator / beam transport system control device, 110: irradiation control device, 111: treatment planning device, 202: dose monitor, 203: position monitor, 204: ridge filter, 205: range shifter, 206: dose monitor control device, 207: position monitor control device, 208: scanning magnet control device, 209: monitor setting control device, 301: current-voltage conversion circuit, 302: voltage-frequency converter, 303: switch, 401: current source, 402: voltmeter, 501: high-voltage power supply, 502: current-voltage conversion circuit, 503: voltage-frequency converter, 601: scatterer, 602: dose monitor, 603: dose monitor signal processing system, 604: monitor setting control device, 605: multi-leaf collimator, 606: collimator control device, 607: ridge filter, 608: bolus

Claims

1. A radiation irradiation system for irradiating an irradiation target with radiation of different intensities, comprising: a radiation monitor unit that detects radiation and acquires radiation information; a monitor control unit that changes a parameter value when the radiation information is detected in accordance with the intensity of the radiation; a determination unit that determines whether the change in the parameter value made by the monitor control unit is correct; A radiation irradiation system comprising:

2. The determination unit determines whether the change in the parameter value is correct before irradiating the irradiation target with the radiation. The radiation delivery system of claim 1 .

3. When the determination unit determines that the change in the parameter value is incorrect, the determination unit outputs warning information. The radiation delivery system of claim 1 .

4. The monitor control unit changes the value of the parameter according to the intensity of the radiation based on treatment plan information for irradiating the radiation to the irradiation target. The radiation delivery system of claim 1 .

5. The parameter is a parameter related to a signal processing circuit that detects the intensity of radiation by the radiation monitor unit. The radiation delivery system of claim 1 .

6. The parameter is a resistance value of a feedback resistor included in the signal processing circuit, which converts a monitor current value detected by the radiation monitor unit into a voltage value. The radiation irradiation system according to claim 5 .

7. a current source for supplying a test current to the feedback resistor; The determination unit determines whether the change in the value of the parameter made by the monitor control unit is correct based on a resistance value of the feedback resistor when the current for inspection is supplied, before irradiating the irradiation target with radiation. The radiation irradiation system according to claim 6 .

8. the radiation monitor unit includes a sensor unit that detects radiation and outputs a current signal, and a signal processing circuit that processes the current signal from the sensor unit and outputs it as the radiation information; The parameter is a parameter for changing the sensitivity of the sensor unit. The radiation delivery system of claim 1 .

9. The sensor unit is an ionization chamber, and the sensitivity of the sensor unit is changed by changing the value of the voltage applied between electrodes included in the ionization chamber as the parameter. The radiation delivery system according to claim 8 .

10. The determination unit, after a parameter for changing the sensitivity of the sensor unit is changed, test-irradiates radiation into a space in which the irradiation target is not present, and determines whether the change of the parameter by the monitor control unit is correct. The radiation delivery system according to claim 8 .

11. The determination unit causes a test irradiation of the radiation to the irradiation target after a parameter for changing the sensitivity of the sensor unit is changed, and subtracts a dose of the test irradiation of the radiation from a target dose described in the treatment plan. The radiation delivery system according to claim 8 .

12. The radiation irradiation system according to any one of claims 1 to 11, an accelerator and a beam transport system for supplying radiation of different intensities to the radiation irradiation system; an irradiation device that irradiates the irradiation target with radiation supplied from the accelerator and the beam transport system; Radiation therapy system.

13. A radiation irradiation method for irradiating an irradiation target with radiation of different intensities by a radiation irradiation system, comprising: the radiation irradiation system includes a radiation monitor unit that detects radiation and acquires radiation information; changing a value of a parameter when the radiation information is detected in accordance with an intensity of the radiation; Determine whether the change in the parameter value is correct Radiation irradiation method.

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