JP2018160465A - Accelerator control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily extract a beam having required arbitrary energy.SOLUTION: An accelerator control system 100 according to an embodiment includes: a beam irradiation control unit 110 for setting required energy level of an acceleration particle; a deflection electromagnet current pattern generation unit 130 that includes current variation pattern data corresponding to clock values and originates a current instruction signal to a deflection electromagnet power supply 12a; a high-frequency pattern generation unit 140 that includes frequency variation pattern data corresponding to the clock values and originates a frequency instruction signal to a high-frequency generation device 14a; and an energy determination/instruction unit 120 that compares a required energy level signal with a present energy corresponding signal to output a signal that advances, by one, the clock values of the current variation pattern data and the frequency variation pattern data when the signals disagree.SELECTED DRAWING: Figure 2

Description

  Embodiments of the present invention relate to an accelerator control system.

  As accelerators for cancer treatment using particle beams such as protons and carbon ions, accelerators such as synchrotrons are used to generate high energy particle beams (hereinafter also referred to as beams). In such a control device for an accelerator, operation is performed so that the maximum energy (top energy) of the charged particles to be accelerated becomes a predetermined value, and the charged particles having the energy can be taken out and used.

  FIG. 11 is a block diagram showing a configuration including a control system of a conventional particle beam therapy accelerator. Here, a configuration for operating a deflection electromagnet 12 that generates a deflection magnetic field for circulating charged particles (for example, protons or carbon ions) of a synchrotron in an orbit as the accelerator 10 is shown. The pattern generator 3 gives a command value for the current of the deflection electromagnet 12 to the deflection electromagnet power source 12a. The deflection electromagnet power supply 12a supplies the deflection electromagnet 12 with a current according to the command value. The pattern generator 3 is operated by the clock signal from the timing device 2. Here, the clock signal is a signal that gives a clock value.

  FIG. 12 is a graph showing an example of an operation pattern of a control system of a conventional particle beam therapy accelerator. That is, it corresponds to the change pattern of the current value from the deflection electromagnet power source 12a. For example, as shown in FIG. 12, the energy of the charged particles is increased from the level of the energy Ei of the incident beam to the level of the energy Ed of the outgoing beam, and when reaching the energy Ed, the state of the energy Ed is maintained and the emission is performed. . Thereafter, the current value is decreased. The pattern generator 3 outputs a waveform having such a pattern. Such a conventional technique is known, for example, from Patent Document 1, Patent Document 2, and Patent Document 3.

Japanese Patent No. 5562627 JP 2001-176700 A JP 2014-22222 A

  The technology of Patent Document 1 relates to a control device that generates an operation pattern according to the beam emission energy, whereby a beam with an arbitrary energy can be taken out and used for treatment. In the case of this technique, pattern data must be created in advance for each required energy.

  The technique of Patent Document 2 stops a clock signal supplied to a pattern generator in order to generate a constant operation pattern at the time of beam extraction. In this case, it is a premise that the beam is emitted when the flat top of the operation pattern is constant, and pattern data must be created in advance for each required energy in the same manner as in Patent Document 1 described above.

  The technique of Patent Document 3 is characterized by having a plurality of deceleration control data for performing beam extraction with a plurality of energies. In this technique, the energy to be used needs to be fixed in advance, and arbitrary energy is not a target. The place where a plurality of deceleration patterns must be provided is the same as the technique of Patent Document 1.

  As described above, in the above-described prior art, it is necessary to prepare in advance pattern data corresponding to the beam energy at the time of emission and to test and confirm that they operate so as to extract the requested energy. .

  In recent years, cancer treatment using particle beams is becoming widespread. In cancer treatment, there is a demand for plane irradiation of a linear beam by scanning. In this case, the depth direction is changed by changing the beam energy. For example, when irradiating at an interval of 1 mm in the depth direction, it is necessary to create 50 energy patterns for an irradiation target having a thickness of 50 mm. This pattern data creation and pattern data switching is complicated. How to realize such a control device has become an issue.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to easily extract a beam having a desired energy.

  In order to achieve the above-described object, the present embodiment obtains the necessary energy of the acceleration particles in an accelerator having a deflection electromagnet that forms a magnetic field in the passage of acceleration particles and a high-frequency acceleration cavity that imparts energy to the acceleration particles. A beam irradiation control unit for setting a required energy level of the accelerated particles, and a current change pattern data for defining a current change pattern with respect to a clock value, and a current command to the power source of the deflection electromagnet A deflection electromagnet current pattern generator for emitting a signal, a frequency change pattern data for defining a frequency change pattern of a high frequency with respect to a clock value, and a high frequency pattern generator for generating a frequency command signal to the high frequency generator of the high frequency acceleration cavity , Indicating the required energy level from the beam irradiation control unit If the signal and the current energy equivalent signal of the accelerated particle are not matched within a predetermined tolerance, a command based on the clock value is sent to each of the deflection electromagnet current pattern generation unit and the high frequency pattern generation unit. An energy determination / command unit that sequentially outputs signals and stops outputting the command signal based on the clock value if they match within a predetermined tolerance, the current value of the current change pattern and the frequency change The change pattern of the energy level corresponding to the frequency of the pattern is a pattern in which the level of the required energy is sequentially reached in the energy decreasing stage after the increase to the energy level higher than the required energy.

  Further, the present embodiment is an accelerator control system for obtaining the necessary energy of the accelerated particles from a deflecting electromagnet that forms a magnetic field in the path of the accelerated particles and an accelerator having a high-frequency acceleration cavity that imparts energy to the accelerated particles. A beam irradiation control unit for setting a required energy level of the accelerated particles, current change pattern data in which a clock value and a current value applied to the deflection electromagnet are associated with each other, and a current command to the power source of the deflection electromagnet A deflection electromagnet current pattern generating unit that emits a signal, and a frequency change pattern data in which a clock value and a frequency are associated with the high frequency generating device of the high frequency accelerating cavity are built in, and a frequency command is sent to the high frequency generating device of the high frequency accelerating cavity A high-frequency pattern generator that emits a signal and a predetermined energy level set in advance. Compare the energy level with the current energy level and the current energy level of the accelerated particle, and if they match, output a signal that advances the clock value of the current change pattern data and frequency change pattern data by a predetermined width And an energy judging / commanding unit.

  According to the embodiment of the present invention, a beam having any desired energy can be easily extracted.

It is a block diagram which shows the structure of the accelerator system which concerns on 1st Embodiment. It is a block diagram which shows the structure of the accelerator control system which concerns on 1st Embodiment. It is a block diagram which shows the structure of the bending electromagnet current pattern generation part of the accelerator control system which concerns on 1st Embodiment. It is a block diagram which shows the structure of the high frequency pattern generation part of the accelerator control system which concerns on 1st Embodiment. It is a flowchart which shows the procedure of the determination / instruction | command method in the energy determination / instruction | command part of the accelerator control system which concerns on 1st Embodiment. It is a graph which shows operation | movement of the accelerator control system which concerns on 1st Embodiment. It is a block diagram which shows the structure of the energy determination and instruction | command part of the accelerator control system which concerns on 2nd Embodiment. It is a block diagram which shows the structure of the accelerator control system which concerns on 3rd Embodiment. It is a flowchart which shows the procedure of the accelerator control method which concerns on 4th Embodiment. It is a graph which shows operation | movement of the control system of the particle beam therapy accelerator which concerns on 4th Embodiment. It is a block diagram which shows the structure including the control system of the conventional particle beam therapy accelerator. It is a graph which shows the example of the driving | operation pattern of the control system of the conventional particle beam therapy accelerator.

  Hereinafter, a control system and a control method for a particle beam therapy accelerator according to an embodiment of the present invention will be described with reference to the drawings. Here, the same or similar parts are denoted by common reference numerals, and redundant description is omitted.

[First Embodiment]
FIG. 1 is a block diagram illustrating a configuration of an accelerator system according to the first embodiment. The accelerator system 500 includes an accelerator 10 and an accelerator control system 100. The accelerator 10 is a synchrotron. The accelerator 10 includes an orbiting beam vacuum vessel 11 around which accelerated particles to be accelerated, a deflecting electromagnet 12, an incident electromagnet 13 for introducing charged particles from a source of charged particles to be accelerated particles, and a high-frequency acceleration cavity. Part 14, an extraction electromagnet 15 for taking out accelerated particles, a circular beam converging quadrupole electromagnet 16 and a quadrupole electromagnet power supply 16a.

  The deflecting electromagnet 12 forms a magnetic field in a direction perpendicular to the traveling plane of the accelerating particles in the circular beam vacuum vessel 11. The circular beam vacuum vessel 11 surrounded by the deflecting electromagnet 12 has a curvature, and the direction of the acceleration particles is changed in this portion. The strength of the magnetic field is increased according to the energy increase of the accelerated particles so that the traveling direction of the accelerated particles always follows this curvature. Specifically, the current supplied from the deflection electromagnet power source 12a, which is the power source of the current of a coil (not shown) of the deflection electromagnet 12, is increased.

  The high-frequency accelerating cavity 14 is a part that supplies energy to so-called high-frequency accelerating cavities, and has members such as a vacuum duct that forms the cavity and a housing outside the vacuum duct. The energy is supplied by increasing the frequency of the high frequency by the high frequency generator 14a.

  As an apparatus for supplying charged particles to be accelerated to the orbiting beam vacuum vessel 11, the accelerator 10 serves as an ion source 17a, an incident accelerator 17b for accelerating charged particles from the ion source 17a, and a path for charged particles. An incident vacuum container 17 is provided. Further, the accelerator 10 includes a beam emission control unit 18 as a device for taking out accelerated particles from the circular beam vacuum vessel 11.

  The accelerator control system 100 controls the accelerator 10 to obtain a predetermined level of required energy for the accelerated particles. Specifically, a current command signal from the accelerator control system 100 to the bending electromagnet power source 12a, a frequency command signal to the high frequency generator 14a, and an output enable signal to the beam extraction control unit 18 are output. The configuration of the accelerator control system 100 will be described with reference to FIG.

  FIG. 2 is a block diagram showing the configuration of the accelerator control system according to the first embodiment. The accelerator control system 100 includes a beam irradiation control unit 110, an energy determination / command unit 120, a deflection electromagnet current pattern generation unit 130, a high frequency pattern generation unit 140, a clock generator 150, and a periodic signal generator 160.

  The beam irradiation control unit 110 sets a required energy level of accelerated particles and outputs a required energy signal. Further, the beam irradiation control unit 110 outputs a determination start signal to the energy determination / command unit 120 at the start of the operation cycle of the accelerator 10.

  FIG. 3 is a block diagram showing the configuration of the deflection electromagnet current pattern generation unit of the accelerator control system. The deflection electromagnet current pattern generator 130 incorporates current change pattern data. The deflection electromagnet current pattern generation unit 130 includes a current change pattern data storage unit 131 and a read circuit 132.

  The current change pattern data stored in the current change pattern data storage unit 131 corresponds to the clock value Cj (j = 1, 2,..., N) as the input variable and the energy level to be given to the accelerated particles as the output variable. The correspondence with the current value ij (j = 1, 2,..., N) of the deflection electromagnet is defined. That is, the current change pattern data is change pattern data of the current value ij with respect to the increase of the clock value Cj.

  The read circuit 132 receives clock values C1, C2,... Sequentially received as clock signals from the energy determination / command unit 120, and current values corresponding to the clock values C1, C2,. .. are sequentially read out and output as current command signals to the deflecting electromagnet power source 12a.

  FIG. 4 is a block diagram showing a configuration of a high-frequency pattern generation unit of the accelerator control system. The high frequency pattern generator 140 contains frequency change pattern data. The high frequency pattern generation unit 140 includes a frequency change pattern data storage unit 141 and a read circuit 142.

  The frequency change pattern data stored in the frequency change pattern data storage unit 141 corresponds to the clock value Cj (j = 1, 2,..., N) as the input variable and the energy level to be given to the accelerated particles as the output variable. The correspondence with the generated frequency fj (j = 1, 2,..., N) of the high-frequency generator 14a is defined. That is, the frequency change pattern data is change pattern data of the frequency fj with respect to the increase of the clock value Cj.

  The read circuit 142 receives clock values C1, C2,... Sequentially received as clock signals from the energy determination / command unit 120, and the frequency f1, corresponding to the clock values C1, C2,. are sequentially read out and output as a frequency command signal to the high-frequency generator 14a.

  The clock generator 150 in FIG. 2 outputs a clock signal. When the series of output patterns is completed, the periodic signal generator 160 outputs a reset signal for resetting to the initial state of the energy change pattern with respect to the time change, that is, the state immediately before starting the energy change pattern. When the reset signal is output, when the energy determination / command unit 120 outputs the clock signal next time, the output clock signal starts from zero.

  The energy determination / command unit 120 in FIG. 2 accepts a signal indicating a required energy level (hereinafter referred to as a required energy signal) and a determination start signal from the beam irradiation control unit 110. In addition, the energy determination / command unit 120 receives a current energy equivalent signal that is a signal corresponding to the current energy of the accelerated particles, and determines whether the level of the current energy equivalent signal has decreased to the level of the required energy level signal. To do.

  Here, as the current energy equivalent signal, a value converted into charged particle energy using a current command signal from the deflection electromagnet current pattern generation unit 130 to the deflection electromagnet power source 12a is used. Alternatively, the current energy equivalent signal may be a value converted into the energy of charged particles using a frequency command signal from the high frequency pattern generator 140 to the high frequency generator 14a. By using a current command signal or a frequency command signal as the current energy equivalent signal, by sending and receiving signals within the same device as the energy determination / command unit 120, that is, the same computer, or an FPGA (Field Programmable Gate Array), etc. A signal corresponding to the current energy can be secured.

  The energy determination / command unit 120 also receives the clock signal generated by the clock generator 150 and the reset signal generated by the periodic signal generator 160.

  When the energy determination / command unit 120 receives the determination start signal from the beam irradiation control unit 110 and determines that the level of the current energy equivalent signal has decreased to the level of the required energy level signal, the energy determination / command unit 120 receives the received clock signal. The output continues to the deflection electromagnet current pattern generator 130 and the high frequency pattern generator 140. The level of the current energy equivalent signal is lowered to the level of the required energy level signal, that is, the determination that the level of the current energy equivalent signal and the level of the required energy level signal match is the same as the level of the current energy equivalent signal and the required energy. This may be done by checking whether the absolute value of the difference from the level signal is smaller than a predetermined value. Hereinafter, this state is expressed as “matched within a predetermined tolerance”.

  When the determination start signal is not received from the beam irradiation control unit 110 or when it is determined that the level of the current energy equivalent signal has reached the level of the required energy level signal, the energy determination / command unit 120 Is not output.

  If it is determined that the level of the current energy equivalent signal has decreased to the level of the required energy level signal, the energy determination / command unit 120 stops the clock signal and then allows the beam extraction control unit 18 to output the beam. Output a signal.

  FIG. 5 is a flowchart showing the procedure of the determination / command method in the energy determination / command unit of the accelerator control system. In the start, a reset signal is output from the beam irradiation control unit 110, and the process starts from a state where the clock signal is reset. First, the presence / absence of a determination start signal from the beam irradiation control unit 110 to the energy determination / command unit 120 is determined (step S01).

  If the determination start signal has not been issued (NO in step S01), the clock is restarted if the clock is stopped (step S06). Also, the output of the beam extraction enable signal is stopped (step S07). Then, the process returns to step S01.

  If it is determined in step S01 that a determination start signal has been issued (step S01 YES), the current energy is calculated from the current energy equivalent signal (step S02). In this state, the clock signal is sequentially output from the energy determination / command unit 120 to the deflection electromagnet current pattern generation unit 130 and the high frequency pattern generation unit 140.

  The energy determination / command unit 120 compares the level of the current energy equivalent signal with the level of the required energy level signal. Here, the required energy level signal starts from the highest level required energy Ed1 (see FIG. 6) at first, and in the case of the next iteration, the next highest level required energy Ed2, and the lower level sequentially. The value falls to the value corresponding to the required energy. These required energies are output from the beam irradiation controller 110 each time in each repeated cycle.

  The energy determination / command unit 120 determines whether the difference between the level of the current energy equivalent signal and the level of the required energy level signal is equal to or less than a specified value by comparison (step S03). If it is not less than the specified value (NO in step S03), step S01 and subsequent steps are repeated.

  If it is determined to be equal to or less than the specified value (YES in step S03), the clock is stopped (step S04). By stopping the clock, acceleration of the accelerating particles is stopped. After step S04, an output enable signal is output to the beam extraction control unit 18 (step S05). After that, when the required energy becomes a value lower than the predetermined level, the clock is restarted, and the energy is lowered to the incident level, and the process returns to step S01.

  FIG. 6 is a graph showing the operation of the accelerator control system. The horizontal axis of FIG. 6 indicates the clock time which is the time set by the clock with the cycle start point set to zero for the cycle described below, and the vertical axis indicates the beam energy of the accelerator 10. First, a reset signal is output from the periodic signal generator 160 at the clock time t1 at the start of this cycle. Immediately after this, the incident energy Ei becomes a constant value level, and during this time, the beam produced by the incident accelerator 17b is incident on the accelerator 10.

  At the clock time t2 for starting acceleration, the accelerator 10 starts increasing the magnetic field of the deflecting electromagnet 12, applying acceleration power in the high-frequency acceleration cavity 14, and increasing the acceleration frequency of the high-frequency generator 14a to increase the energy of the accelerated particles. Let The acceleration is completed at time t3 when acceleration is performed up to the maximum energy Em.

  After a short time from the acceleration completion clock time t 3, the deceleration start clock time t 4 is reached, and the beam irradiation control unit 110 outputs a determination start signal to the energy determination / command unit 120. The beam irradiation control unit 110 also outputs the highest level required energy signal to the energy determination / command unit 120. As a result, the energy determination / command unit 120 starts comparing and determining the current energy equivalent signal and the required energy level signal.

  Thereafter, as the clock time advances from clock time t4, the current value corresponding to the clock value in the current change pattern data and the frequency value corresponding to the clock value in the frequency change pattern data decrease. For this reason, the magnetic field in the deflection electromagnet 12 and the acceleration frequency in the high-frequency acceleration cavity 14 are lowered, and the beam of accelerated particles decelerates by applying energy to the high-frequency generator 14a.

  When the current energy equivalent signal matches the level signal of the required energy Ed1 within a predetermined tolerance at the clock time t5, the energy determination / command unit 120 includes the deflection electromagnet current pattern generation unit 130 and the high frequency pattern generation unit. The clock output to 140 is stopped. For this reason, the deflection electromagnet current pattern generation unit 130 does not update the current command signal, and the high frequency pattern generation unit 140 does not update the frequency command signal, and each becomes a constant value. As a result, the energy of the accelerated particles becomes constant.

  When the current energy equivalent signal matches the level signal of the maximum required energy Ed1 in the required energy within a predetermined tolerance, the energy determination / command unit 120 sends an output enable signal to the beam extraction control unit 18. Output. In response to this, the beam emission control unit 18 emits accelerated particles.

  After the emission of the accelerated particles, from the clock time t6, the energy determination / command unit 120 starts comparing and determining the current energy equivalent signal and the required energy level corresponding to the required energy level Ed2 next to Ed1.

  When the current energy equivalent signal matches the level signal of the required energy Ed2 within a predetermined tolerance at clock time t7, the energy determination / command unit 120 includes the deflection electromagnet current pattern generation unit 130 and the high frequency pattern generation unit. The clock output to 140 is stopped, and the energy of the accelerated particles becomes constant. The current energy equivalent signal matches the level signal of the required energy Ed2 within a predetermined tolerance, and the energy determination / command unit 120 outputs an extraction enable signal to the beam extraction control unit 18. In response to this, the beam emission control unit 18 emits accelerated particles.

  At clock time t8, energy reduction of the accelerated particles starts again. If there is a next level of required energy, follow the same process. If there is no required energy at the next level, the energy of the accelerated particles is reduced to the stop state, and the energy of the accelerated particles is reduced to the incident level at clock time t9.

  The maximum energy Em is higher than Ed1 and Ed2. Moreover, it is desirable that the maximum energy Em in each cycle be equal to each other. This is because there is a hysteresis in the magnetic flux characteristics with respect to the current of the deflection electromagnet 12, and when the maximum current corresponding to the maximum energy Em is different, the magnetic flux characteristics with respect to the current of the deflection electromagnet 12 are different. If this characteristic is different, the current pattern corresponding to the current value corresponding to the energy changes the pattern data, the frequency change pattern data that specifies the relationship to the clock value of the frequency corresponding to the energy, the entire pattern each time, This is because it needs to be maintained.

  Note that the maximum energy Em is not limited to the same value. For example, when there are a plurality of levels as the maximum energy Em and the characteristics of the magnetic flux with respect to the current of the deflection electromagnet 12 are known for each, the current of the deflection electromagnet 12 with respect to the maximum energy Em of the plurality of levels is known. Since the characteristics of the magnetic flux can be prepared, even if any of these is selected, the current change pattern data and the frequency change pattern data corresponding to the selected characteristic may be selected.

  In the description, the case where the required energy is two levels of Ed1 and Ed2 is shown, but the present invention is not limited to this. Basically, the required energy may be one or three or more. It is the same.

  In the conventional technique, when the level of required energy changes or when the number of required energy levels changes, it is necessary to create pattern data corresponding to each level. On the other hand, according to the present embodiment configured as described above, even in such a case, by preparing one type of data as current change pattern data and frequency change pattern data, any desired energy can be obtained. Thus, it becomes easy to realize higher-level treatment irradiation such as scanning irradiation.

  In the case of cancer treatment or the like, conventionally, when there are multiple depths of the irradiated part, the energy increase, irradiation (extraction), and energy decrease cycle patterns are required for each of the required energy according to each depth. It was necessary to carry out sequential operation. On the other hand, according to the present embodiment, irradiation with accelerated particles of a plurality of energies can be performed in one cycle pattern, so that the entire operation time can be shortened and the burden on the patient can be reduced. .

[Second Embodiment]
FIG. 7 is a block diagram showing the configuration of the energy determination / command unit of the accelerator control system according to the second embodiment. This embodiment is a modification of the first embodiment. In the second embodiment, the energy determination / command unit 120 includes a comparison determination circuit 121, a clock counter 122, an energy pattern data storage unit 123, and a clock value read circuit 124.

  The energy pattern data storage unit 123 has energy change pattern data. The energy change pattern data includes energy values Ej (j = 1, 2,..., N) to be given to the accelerated particles as input variables and clock values Cj (j = 1, 2) corresponding to the energy levels as output variables. ,..., N). That is, the energy change pattern data is change pattern data of the clock value Cj with respect to an increase in the energy value Ej. That is, the energy change pattern data is data in the opposite direction to the current change pattern data or the frequency change pattern data, and can be said to be inverse function data that gives a clock value for energy with respect to the energy level change pattern.

  The clock value reading circuit 124 receives the required energy values Ed1 and Ed2 that are sequentially received from the beam irradiation control unit 110, and sequentially receives the clock values Cm, Cd1, and Cd2 corresponding to the required energy values Em, Ed1, and Ed2 from the frequency change pattern data. Read out and output a clock value to the deflection electromagnet current pattern generator 130 and the high frequency pattern generator 140. Clock values Cm, Cd1, and Cd2 are set based on clock times tm, t5, and t7.

  In the second embodiment, the energy determination / command unit 120 calculates a current energy equivalent signal to be compared with the required energy level signal by using the output of the clock value readout circuit 124.

  That is, the output of the clock value reading circuit 124, the current value corresponding to the clock value of the current pattern data of the deflecting electromagnet current pattern generator 130 that has received the output of the clock value reading circuit 124, and the deflection electromagnet power source based on this current value The magnetic flux in the deflection electromagnet based on the command and the current from the deflection electromagnet power supply has a one-to-one correspondence.

  Also, the output of the clock value reading circuit 124, the frequency corresponding to the clock value of the frequency pattern data of the high frequency pattern generation unit 140 that has received the output of the clock value reading circuit 124, the command to the high frequency generator 14a based on this frequency, the high frequency The frequency in the high frequency cavity by the generator 14a corresponds one to one.

  As a result, there is a one-to-one correspondence with the energy of the accelerated particles. Moreover, since it is based on the exchange of electrical signals and computation, the correspondence relationship is established in a time sufficiently shorter than the change due to the clock. Therefore, it is appropriate to calculate the current energy equivalent signal by using the output of the clock value reading circuit 124.

  By using the output of the clock value readout circuit 124 as the current energy equivalent signal, the same device as the energy determination / command unit 120, that is, the same computer, or FPGA (Field Programmable Gate Array) as in the first embodiment. ) Etc., the current energy equivalent signal can be secured.

  As described above, also in this embodiment, the same effect as that of the first embodiment can be obtained.

[Third Embodiment]
FIG. 8 is a block diagram showing a configuration of an accelerator control system according to the third embodiment. This embodiment is a modification of the first embodiment. In the third embodiment, the energy signal from the energy measuring unit 18a is used as the current energy equivalent signal to be compared with the required energy signal by the energy determination / command unit 120.

  By directly using the signal from the energy measuring unit 18a, it becomes possible to compare with the energy of the accelerated particles of the actual irradiation beam, and the control accuracy is improved.

[Fourth Embodiment]
This embodiment is a modification of the first embodiment. FIG. 9 is a flowchart showing the procedure of the accelerator control method according to the fourth embodiment. In the fourth embodiment, prior to determining whether or not the current energy matches the required energy within a predetermined tolerance (step S03), the current energy is an allowable value that is predetermined to the required energy + ΔE. It is determined whether or not they match within the difference (step S11).

  If it is not determined that the current energy matches the required energy + ΔE within a predetermined tolerance (NO in step S11), steps S01 and after are repeated. If it is determined that the current energy matches the required energy + ΔE within a predetermined tolerance (YES in step S11), it is next determined whether or not the current energy matches the required energy (step S11 YES). Step S03).

  If it is determined that the current energy matches the required energy within a predetermined tolerance (YES in step S03), the clock is stopped (step S04) and a beam extraction enable signal is output (step S05).

  When it is determined that the current energy does not match the required energy within a predetermined tolerance (NO in step S03), the clock cycle T is increased by kΔT, and step S01 and subsequent steps are repeated. Note that k is an arbitrary positive real number. That is, the clock value which is a command signal to each of the deflection electromagnet current pattern generation unit 130 and the high frequency pattern generation unit 140 is sequentially increased by a predetermined width.

  FIG. 10 is a graph showing the operation of the control system of the particle beam therapy accelerator according to the fourth embodiment. FIG. 10 shows a case where k = 1, that is, a case where the clock period increases by ΔT.

  In the first embodiment, as shown by “constant cycle operation” in FIG. 10, the current energy pattern decreases stepwise in this cycle and reaches the required energy. By determining that the required energy has been reached, the energy requirement becomes a constant value, so that the gradient of change becomes discontinuous, as shown as part A in FIG.

  There is a slight delay time from when the current command from the deflection electromagnet current pattern generator 130 is output until the current of the deflection electromagnet 12 appears and becomes the magnetic force of the deflection electromagnet 12. Similarly, a slight delay time exists for the frequency in the high frequency generator 14a from the output of the frequency command from the high frequency pattern generator 140. For this reason, the accuracy of the current control of the deflection electromagnet 12 and the frequency control in the high-frequency accelerating cavity portion 14 are lowered in a portion where there is a discontinuous change gradient such as the portion A. If the accuracy of these controls decreases, a part of the beam of accelerated particles in the accelerator 10 is lost.

  In the fourth embodiment, it is possible to prevent a reduction in control accuracy by smoothing the change from the energy level of the required energy + ΔE.

[Other Embodiments]
As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. Moreover, you may combine the characteristic of each embodiment.

  Furthermore, these embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention.

  These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 2 ... Timing apparatus, 3 ... Pattern generator, 10 ... Accelerator, 11 ... Circulating beam vacuum container, 12 ... Deflection electromagnet, 12a ... Deflection electromagnet power supply, 13 ... Incident electromagnet, 14 ... High frequency acceleration cavity, 14a ... High frequency Generating device 15 ... Electromagnet for extraction, 16 ... Quadrupole electromagnet for converging circular beam, 16a ... Quadrupole electromagnet power source, 17 ... Vacuum container for incidence, 17a ... Ion source, 17b ... Accelerator for incidence, 18 ... Beam extraction controller, 18a DESCRIPTION OF SYMBOLS ... Energy measurement part, 100 ... Accelerator control system, 110 ... Beam irradiation control part, 120 ... Energy judgment / command part, 121 ... Comparison judgment circuit, 122 ... Clock counter, 123 ... Energy pattern data storage part, 124 ... Clock value reading Circuit 130... Deflecting electromagnet current pattern generation unit 131 131 current change pattern data storage unit 32 ... read circuit, 140 ... RF pattern generating section, 141 ... frequency variation pattern data storage unit, 142 ... read circuit 150 ... clock generator, 160 ... periodic signal generator, 500 ... accelerator system

Claims (3)

An accelerator control system for obtaining a necessary energy of the accelerated particles from a deflecting electromagnet that forms a magnetic field in a path of the accelerated particles and an accelerator having a high-frequency acceleration cavity that imparts energy to the accelerated particles,
A beam irradiation control unit for setting a required energy level of the accelerated particles;
Built-in current change pattern data in which a clock value and a current value to be applied to the deflection electromagnet are associated with each other, and a deflection electromagnet current pattern generator that issues a current command signal to the power source of the deflection electromagnet,
A frequency change pattern data in which a clock value is associated with a frequency in the high-frequency generator of the high-frequency acceleration cavity, and a high-frequency pattern generator that issues a frequency command signal to the high-frequency generator of the high-frequency acceleration cavity;
An energy determination that compares the set required energy level with the current energy level of the accelerated particles and outputs a signal that advances the clock value of the current change pattern data and the frequency change pattern data if they do not match. A command section;
An accelerator control system comprising: An accelerator control system for obtaining a necessary energy of the accelerated particles from a deflecting electromagnet that forms a magnetic field in a path of the accelerated particles and an accelerator having a high-frequency acceleration cavity that imparts energy to the accelerated particles,
A beam irradiation control unit for setting a required energy level of the accelerated particles;
Built-in current change pattern data in which a clock value and a current value to be applied to the deflection electromagnet are associated with each other, and a deflection electromagnet current pattern generator that issues a current command signal to the power source of the deflection electromagnet,
A frequency change pattern data in which a clock value is associated with a frequency in the high-frequency generator of the high-frequency acceleration cavity, and a high-frequency pattern generator that issues a frequency command signal to the high-frequency generator of the high-frequency acceleration cavity;
The energy level obtained by adding a predetermined positive energy width to the set required energy level is compared with the current energy level of the accelerating particles, and if they match, the current change pattern data and the frequency change pattern data An energy determination / command unit that outputs a signal to advance the clock value of a predetermined width;
An accelerator control system comprising: The energy level change pattern corresponding to the current value of the current change pattern and the frequency of the frequency change pattern is sequentially changed to the level of the required energy in an energy decrease stage after increasing to an energy level higher than the required energy. The pattern to reach,
The accelerator control system according to claim 1 or 2, wherein

Images