JP5111233B2 - Particle beam therapy system - Google Patents

Description

  The present invention relates to a particle beam therapy system capable of high-precision treatment irradiation, and more particularly to a particle beam therapy system suitable for using a spot scanning irradiation method.

  Reflecting the recent aging society, as one of the cancer treatment methods, radiotherapy that is minimally invasive, has less burden on the body, and can maintain a high quality of life after treatment is attracting attention. Among them, a particle beam therapy system using a charged particle beam such as proton or carbon accelerated by an accelerator is particularly promising because of excellent dose concentration on the affected area. The particle beam therapy system consists of an accelerator such as a synchrotron and cyclotron that accelerates the beam generated by the ion source to near the speed of light, a beam transport system that transports the emitted beam of the accelerator, and a beam that matches the position and shape of the affected area. It is comprised from the irradiation apparatus which irradiates to.

  By the way, in the irradiation apparatus of the particle beam therapy system, conventionally, when irradiating a beam according to the shape of the affected part, the beam diameter is enlarged with a scatterer, and then the peripheral part is shaved with a collimator to shape the beam. However, in this method, the beam utilization efficiency is poor, unnecessary neutrons are easily generated, and the degree of coincidence with the shape of the affected area is limited. Thus, recently, as a more accurate irradiation method, there is an increasing market need for a scanning irradiation method in which a thin beam from an accelerator is deflected by an electromagnet and scanned according to the shape of an affected area.

  In the scanning irradiation method, a three-dimensional affected part shape is divided into a plurality of layers in the depth direction, and each layer is further divided two-dimensionally to set a plurality of irradiation spots. In the depth direction, the energy of the irradiation beam is changed to selectively irradiate each layer, and within each layer, the irradiation beam is two-dimensionally scanned with an electromagnet to give a predetermined dose to each irradiation spot. A method of continuously turning on the irradiation beam while moving between irradiation spots is referred to as raster scanning, and a method of turning off the irradiation beam during movement is referred to as spot scanning.

  In the conventional spot scanning method, each beam spot is irradiated with a predetermined dose while the beam scanning is stopped. After the irradiation beam is turned off, the excitation amount of the scanning electromagnet is changed to move to the next beam spot. Therefore, in order to realize high-precision treatment irradiation by the spot scanning method, high-speed ON / OFF, particularly high-speed cutoff (OFF) is indispensable together with the irradiation beam position accuracy.

  From the viewpoint of the positional accuracy of the irradiation beam, a beam emitting method from the synchrotron is known in which the size of the circulating beam is increased at a high frequency and emitted from a particle having a large amplitude exceeding the stability limit. In this method, the operating parameters of the synchrotron emission-related equipment can be set constant during the emission, so that the orbit stability of the emission beam is high and the high positional accuracy of the irradiation beam required for the spot scanning method can be achieved.

  However, even if the emission high frequency is turned off at the end of irradiation of each spot, it takes time until the emission beam is interrupted, so irradiation during this delay time (delayed irradiation) occurs. In the spot scanning method, it is essential to reduce this delayed irradiation dose as much as possible from the viewpoint of dose accuracy. Therefore, the breaking electromagnet installed in the beam transport system is turned ON / OFF so that the emitted beam of the synchrotron does not reach the irradiation device between the irradiation spots. For example, in Patent Document 1, an outgoing beam is deflected by a breaking electromagnet disposed in a linear portion of a beam transport system, and unnecessary beam components that cause delayed irradiation are discarded by a beam dump disposed downstream of the linear portion. .

  On the other hand, there is a problem of delayed irradiation when the accelerator is a cyclotron. The cyclotron controls the ion source applied voltage to turn on / off the emitted beam, but it takes time until the emitted beam is cut off even if the ion source applied voltage is turned off at the end of irradiation of each spot. For this reason, the measures disclosed in Patent Document 1, for example, are implemented in the same manner as the synchrotron.

JP 2005-332794 A

  However, for example, in the prior art described in Patent Document 1, the cut-off time of the outgoing beam reaches several hundreds of μs, and it has been difficult to reduce it to within several tens of μs required by the spot scanning method. That is, the excitation power source is high voltage and requires a large current output and is expensive, and the breaking electromagnet is increased in size to enhance withstand voltage characteristics and heat-resistant cooling characteristics. On the other hand, if the linear part drift distance of the beam transport system between the breaker magnet and the beam dump is extended to alleviate the required performance of the breaker magnet and excitation power source, there is a problem that the overall system becomes larger and the beam transport adjustment becomes difficult. there were.

  An object of the present invention is to provide a particle beam therapy system that improves the dose accuracy by shortening the blocking time of the outgoing beam.

  In order to achieve the above object, the present invention provides an acceleration device that accelerates and emits a charged particle beam to a predetermined energy, an irradiation device that emits a charged particle beam to an irradiation target, and a charged particle emitted from the acceleration device. A beam transport system that guides the beam to the irradiation device; and a beam blocking device that is installed in the beam transport system and blocks the supply of the charged particle beam to the irradiation device, and the beam blocking device passes through the beam transport system. A first breaking electromagnet for deflecting the particle beam and a second breaking electromagnet having a response speed different from that of the first breaking electromagnet are provided.

  The present invention also provides an acceleration device that accelerates and emits a charged particle beam to a predetermined energy, an irradiation device that emits a charged particle beam to an irradiation target, and a beam that guides the charged particle beam emitted from the acceleration device to the irradiation device. And a beam blocking device that is installed in the beam transport system and blocks the supply of the charged particle beam to the irradiation device, and the beam blocking device is a plurality of different response speeds installed on the entrance side of the charged particle beam. And a beam dump installed on the exit side of the charged particle beam.

  Furthermore, the present invention provides a charged particle guided by a beam transport system in which the breaking magnets having two different response speeds in the particle beam therapy system generate a dipole magnetic field component having substantially opposite polarity. The beam is deflected in the opposite direction.

  ADVANTAGE OF THE INVENTION According to this invention, the interruption | blocking time of an emitted beam can be shortened, and the particle beam therapy system which improved the dose precision can be implement | achieved.

[First Embodiment]
Hereinafter, the configuration and operation of the particle beam therapy system according to the first embodiment of the present invention will be described with reference to FIGS. First, the overall configuration of the particle beam therapy system according to the present embodiment and the irradiation principle of the particle beam will be described with reference to FIGS. FIG. 1 is a system configuration diagram showing the configuration of the particle beam therapy system according to the first embodiment of the present invention.

  The particle beam therapy system 100 includes a pre-accelerator 11 such as a linac, a synchrotron 200 that emits after accelerating a charged particle beam preliminarily accelerated by the pre-accelerator 11 to a predetermined energy, and a charged particle beam emitted from the synchrotron. Is composed of a beam transport system 300 that guides the patient to the treatment room 400, an irradiation device 500 that irradiates a charged particle beam in accordance with the shape of the affected part of the patient 41 in the treatment room 400, and a control device 600.

  The synchrotron 200 includes an incident device 24 that receives a charged particle beam preliminarily accelerated by the pre-accelerator 11, a deflecting electromagnet 21 that deflects the charged particle beam and circulates in a fixed orbit, and a horizontal so that the charged particle beam does not spread. / Convergent / divergent type quadrupole electromagnet 22 that gives a converging force in the vertical direction, acceleration cavity 25 that accelerates the charged particle beam to a predetermined energy with a high-frequency acceleration voltage, and stable against vibration amplitude of the circulating charged particle beam A hexapole electromagnet 23 that forms a limit; an output device 26 that increases the vibration amplitude of a charged particle beam in a high-frequency electromagnetic field and exceeds the stability limit; and outputs a high-frequency power for output to the output device 26. And an output deflecting device 27 that deflects to emit a charged particle beam.

  Here, with reference to FIG. 2, a method of emitting a charged particle beam from the synchrotron in the particle beam therapy system according to the present embodiment will be described. FIG. 2 is an explanatory diagram of a method of emitting a charged particle beam from the synchrotron 200 in the particle beam therapy system 100 according to the first embodiment of the present invention.

  FIG. 2 shows the state of the charged particle beam circulating around the synchrotron in a horizontal phase space related to emission. The horizontal axis is the deviation (position P) from the design trajectory, and the vertical axis is the inclination (angle θ) with respect to the design trajectory. FIG. 2A shows a horizontal phase space before the start of emission. FIG. 2B shows a horizontal phase space after the start of emission.

  As shown in FIG. 2A, each particle constituting the charged particle beam circulates as a circular beam BM while vibrating in the horizontal / vertical direction around the design trajectory. Here, by exciting the hexapole electromagnet 23 shown in FIG. 1, a triangular stable region SA is formed in the phase space. The particles in the stable region continue to circulate stably in the synchrotron 200.

  At this time, when an output high frequency is applied to the output device 26 shown in FIG. 1, the amplitude of the circular beam BM increases as shown in FIG. 2B. Then, the particles that have moved out of the stable region SA suddenly increase in vibration amplitude along the outgoing branch EB, and finally jump into the opening OP of the outgoing deflection device 27 to be output as the outgoing beam B from the synchrotron. It is taken out.

  The size of the stable region is determined by the amount of excitation of the convergence / divergence type quadrupole electromagnet 22 or hexapole electromagnet 23. FIG. 2A shows a phase space before the start of emission, and FIG. 2B shows a phase space after the start of emission. The size of the stable region is set larger than the emittance (area occupied by the phase space) of the charged particle beam before the start of extraction. When the emission starts, a high frequency electromagnetic field for emission is applied to increase the emittance of the charged particle beam (increase the vibration amplitude of the particle), and the particle is emitted from the particle exceeding the stability limit. In this state, by turning ON / OFF the high frequency electromagnetic field for emission, ON / OFF of the emission beam can be controlled. The feature of this extraction method is that the position and size of the emission beam are stable and an irradiation beam suitable for the scanning method can be obtained because the excitation amount of the electromagnet is constant during the emission and the stable region and the emission branch are unchanged.

  Referring again to FIG. 1, the beam transport system 300 includes a deflecting electromagnet 31 that deflects the outgoing beam of the synchrotron 200 with a magnetic field and guides it to the treatment room 400 along a predetermined design trajectory, and prevents the charged particle beam from spreading during transportation. A converging / diverging type quadrupole electromagnet 32 that applies a converging force in the horizontal / vertical direction and a beam blocking device 700 for turning on / off the supply of the charged particle beam to the irradiation device 500 in the treatment room.

  The beam blocking device 700 includes two breaking electromagnets (high-speed breaking electromagnets) 33, (low-speed breaking electromagnets) 34, excitation power supplies 33A and 34A for exciting each of the two breaking electromagnets 33 and 34, and breaking electromagnets 33, It comprises a beam dump 35 for discarding the beam component removed at 34. An excitation power source 33A is connected to the breaking electromagnet 33, and an excitation power source 34A is connected to the breaking electromagnet 34. The control device 600 is connected to the excitation power supplies 33A and 34A and controls them. The breaking electromagnet 33 and the excitation power supply 33A are for high-speed response / short-time operation at the start of breaking, and the breaking electromagnet 34 and excitation power supply 34A are for low-speed response / long-time operation during the subsequent interruption period. The operation sequence will be described later with reference to FIG.

  The breaking electromagnets 33 and 34 include a method of deflecting an unnecessary beam component with a dipole magnetic field when excited and discarding it with a beam dump 35, and an irradiation apparatus 500 only for the beam component deflected with a dipole magnetic field when excited. There are ways to supply. The former is easy to adjust the beam transport system, and the latter is highly safe because the supply of the charged particle beam to the irradiation device is interrupted when the equipment is abnormal. Either method is possible, but in the present embodiment, the former case is described.

  The irradiation apparatus 500 includes a scanning electromagnet power supply 500A. Here, the configuration of the irradiation apparatus 500 used in the particle beam therapy system according to the present embodiment will be described with reference to FIG. FIG. 3 is a front view showing a configuration of an irradiation apparatus 500 used in the particle beam therapy system 100 according to the first embodiment of the present invention.

  The irradiation apparatus 500 includes a scanning electromagnet 51 that deflects the charged particle beam guided by the beam transport system 300 in the horizontal and vertical directions and performs two-dimensional scanning according to the cross-sectional shape of the affected part 42, and a power source 500 </ b> A of the scanning electromagnet 51. And various beam monitors 52a and 52b for monitoring the position, size (shape) and dose of the charged particle beam.

  Here, the spot scanning method will be described with reference to FIGS. FIG. 3B is an explanatory view of the irradiation beam as viewed from the upstream side.

  As shown in FIG. 3A, with respect to the affected part 42 of the patient 41, the affected part shape is divided into a plurality of layers in a three-dimensional depth direction, and each layer is further divided two-dimensionally to obtain a plurality of parts. Set the irradiation spot. In the depth direction, each layer is selectively irradiated by changing the energy of the irradiation beam by changing the energy of the emission beam of the synchrotron 200 or the like. In each layer, as shown in FIG. 3B, the irradiation beams SP are two-dimensionally scanned by the scanning electromagnets 51a and 51b to give a predetermined dose to each irradiation spot SP. When the dose of one irradiation spot SP expires, the irradiation beam is interrupted at a high speed, and then the irradiation beam is turned off to move to the next irradiation spot.

  Next, the operation of the spot scanning method by the particle beam therapy system 100 of the present embodiment will be described using FIG. FIG. 4 is a timing chart showing the operation of the spot scanning method by the particle beam therapy system 100 according to the first embodiment of the present invention.

  In FIG. 4, the horizontal axis indicates time t. The vertical axis in FIG. 4A indicates the scanning electromagnet current supplied from the power supply 500 </ b> A to the scanning electromagnet 51 in accordance with the scanning command signal supplied from the control device 600 to the power supply 500 </ b> A of the scanning electromagnet 51. The vertical axis in FIG. 4B indicates the high frequency power for emission supplied from the power supply 26A to the emission device 26 in accordance with the high frequency control signal for emission supplied from the control device 600 to the power supply 26A of the emission device 26. Yes. The vertical axis in FIG. 4C indicates the outgoing beam emitted from the synchrotron 200 to the beam transport system 300. In FIG. 4D, the vertical axis indicates ON / OFF of the excitation current supplied from the power supply 33A to the high-speed cutoff electromagnet 33 in accordance with the beam cutoff control signal supplied from the control device 600 to the power supply 33A of the high-speed cutoff electromagnet 33. Indicates the state. Similarly, the vertical axis of FIG. 4E represents the ON of the excitation current supplied from the power supply 34A to the low-speed cutoff electromagnet 34 in response to the beam cutoff control signal supplied from the control device 600 to the power supply 34A of the low-speed cutoff electromagnet 34. / OFF state. The vertical axis | shaft of FIG.4 (F) has shown the ON / OFF state of the irradiation beam irradiated from the irradiation apparatus 500. FIG. When the irradiation beam is ON, spots S1, S2, S3 and S4 are formed.

  As shown in FIG. 4A, by increasing the scanning electromagnet current supplied from the power source 500A to the scanning electromagnet 51, the irradiation position of the irradiation beam is scanned, and the scanning electromagnet supplied from the power source 500A to the scanning electromagnet 51. By making the current constant, the irradiation position of the irradiation beam can be made constant. In the spot scanning method, as shown in FIGS. 4A and 4F, a predetermined dose is irradiated to each of the irradiation spots S1, S2, and S3 while the beam scanning is stopped, and the irradiation beam is turned off. Then, the excitation amount of the scanning electromagnet is changed to move to the next irradiation spot.

  At the time of spot irradiation for supplying a charged particle beam to the irradiation device 500, as shown in FIG. 4B, the high-frequency electromagnetic field applied to the emission device 26 is turned on to block the supply of the charged particle beam to the irradiation device 500. During high-speed movement, the high-frequency electromagnetic field applied to the extraction device 26 is turned off. When the supply of the charged particle beam to the irradiation device 500 is cut off, as shown in FIGS. 4D and 4E, two units with different response speeds and energization times installed in the beam transport system 300 are simultaneously used. The supply of charged particle beam is cut off at high speed by exciting the breaking electromagnet. In this embodiment, when the breaking electromagnets 33 and 34 are excited, the charged particle beam passing through the beam trajectory in the beam transport system 300 is deflected from the beam trajectory and collides with the beam dump 35 and is discarded. On the other hand, when the breaking electromagnets 33 and 34 are not excited, the charged particle beam passes through the beam trajectory of the beam transport system 300 and is supplied into the irradiation apparatus 500. As shown in FIG. 4C, the charged particle beam is emitted (delayed irradiation) from the synchrotron 200 even after the emission high-frequency power (FIG. 4B) of the emission device 26 is stopped. The delayed charged particle beam is blocked at a high speed by the beam blocking device 700. After turning off the high-frequency power for extraction of the extraction device 26, the excitation amount by the high-speed breaking electromagnet 33 is raised at high speed. Thereafter, the amount of excitation is increased using the low-speed interrupting magnet 34. The control device 600 manages and controls the ON / OFF timing of the high-frequency electromagnetic field applied to the extraction device 26 and the excitation timing of the two breaking electromagnets.

  Here, the features of the present embodiment will be described in comparison with the above-described prior art. FIG. 14 is a system configuration diagram showing the configuration of a conventional particle beam therapy system 100B. The beam blocking device 700B includes a single breaking electromagnet 36 and its excitation power source 37. FIG. 15 is a timing chart showing the operation of the spot scanning method in the conventional particle beam therapy system 100B.

  In order to realize high-speed beam blocking by the conventional technique, one interrupting magnet 36 is excited by one excitation power source 37, and the excitation current is increased after a sharp rise as shown by the broken line in FIG. It must be maintained at a constant value over time. In particular, when irradiating a remote spot at a position where the irradiation spot is distant, the beam scanning time, that is, the irradiation beam OFF time becomes long, and the excitation time reaches a maximum of several tens of ms. Therefore, the excitation power source 37 is required to have a high voltage, a large current, and a high duty output, and is extremely expensive. The breaking electromagnet 36 is complicated and enlarged because of the enhancement of withstand voltage characteristics and heat-resistant cooling characteristics. Therefore, in the prior art, as shown by the solid lines in FIGS. 15E and 15F, the cut-off time of the outgoing beam actually reaches several hundreds of μs and can be shortened to several tens of μs required by the spot scanning method. It was difficult. In order to alleviate the required performance of the breaking electromagnet 36 and the excitation power source 37, there is also a method of reducing the necessary exciting current by extending the linear part drift distance of the beam transport system between the breaking electromagnet 36 and the beam dump 35. In this case, there is a big problem that leads to an increase in the size of the entire system and difficulty in adjusting the beam transport.

  On the other hand, in the present embodiment, the breaking magnet and the excitation power source constituting the beam blocking device 700 are respectively used for high-speed response / short-time operation (33, 33A) at the start of interruption and low-speed response / long-time operation during the subsequent interruption period. (34, 34A) for functional separation. According to the present embodiment, since the functions are separated into two for high-speed response and low-speed response, the required performance can be easily achieved, and a design optimized for each operating condition becomes possible. The device can be reduced in size and cost. That is, in this case, an ideal excitation current as shown by a broken line in FIG. 15E can be effectively achieved by using two breaker magnets and excitation power sources that can be easily manufactured. In the present embodiment, functions are separated for high-speed response and low-speed response in one beam blocking device 700, but a beam blocking device having each function may be provided separately. In this case, the first breaking electromagnet device 701 for high-speed response has the first breaking electromagnet 33 and the first excitation power supply 33A, and the second breaking electromagnet device 702 for low-speed response is the second breaking electromagnet 34. And a second excitation power supply 34A.

  FIG. 5 is a cross-sectional view showing the structure of the breaking electromagnet of the beam blocking device 700 used in the particle beam therapy system according to the first embodiment of the present invention. FIG. 5A shows an example of the structure of the high-speed breaking electromagnet 33. The magnetic core 71 constitutes a C-type electromagnet, and the material used for the magnetic core 71 in response to high-speed excitation is a material that hardly flows eddy current, such as ferrite, amorphous, nano-fine crystalline soft magnetic alloy, etc. Select. Similarly, the beam duct 72 is made of ceramics for countermeasures against eddy currents. The exciting coil 73 is designed with the number of coil turns of several tens of turns or less in order to suppress the inductance of the electromagnet and reduce the applied voltage. On the other hand, the excitation current increases because the number of coil turns is reduced, but by limiting the excitation time to a short time at the start of shut-off, it is possible to design a structure that can be cooled only by air cooling while suppressing average power consumption (heat generation amount). . Therefore, the withstand voltage performance and the cooling performance can be relaxed.

  FIG. 5B shows an example of the structure of the low-speed breaking electromagnet 34. The magnetic core 71 constitutes a window frame type electromagnet, and the material used for the magnetic core 71 is an eddy current such as a laminated steel plate as in various electromagnets installed in the synchrotron 200 and the beam transport system 300. Select a material that does not flow properly. Similarly, the beam duct 72 is made of thin-walled stainless steel to reduce eddy currents. The exciting coil 73 is designed to have a structure in which the number of turns is increased to about several hundred turns, the exciting current is kept small within a range where the inductance does not become extremely large, the average power consumption (heat generation amount) is reduced, and cooling can be performed only by air cooling. it can. Therefore, the withstand voltage performance and the cooling performance can be relaxed.

  FIG. 6 is an equipment configuration diagram showing the configuration of the excitation power source of the beam blocker 700 used in the particle beam therapy system according to the first embodiment of the present invention. FIG. 6A shows an example of the device configuration of an excitation power source 33 </ b> A that excites the high-speed breaking electromagnet 33. The excitation power source 33A inputs an input unit 74 that converts AC power received from a commercial power source into an appropriate voltage value, a transformer / rectifier unit 75 that converts the AC power into DC power having a required voltage value, and the DC power. The pulse shaping unit 76 that charges and discharges the capacitor, the control unit 77 that adjusts the charging and discharging timing of the capacitor based on the timing control signal from the control device 600, and the pulse excitation current are output to the high-speed breaking electromagnet 33 and the reflected power is absorbed. An output unit 78 is included. The rise time of the excitation current of the high-speed breaking electromagnet 33 is determined by the capacitance of the capacitor of the pulse shaping unit 76 and the inductance of the high-speed breaking electromagnet 33. On the other hand, the fall time of the excitation current is determined by the resistance value of the attenuation resistor of the output unit 78 that absorbs the inductance of the high-speed breaking magnet 33 and the reflected power. Since the inductance of the high-speed breaking electromagnet 33 is small, the excitation power supply 33A can be realized by an inexpensive pulse power supply with a low charging voltage.

  FIG. 6B shows an example of the device configuration of an excitation power supply 34 </ b> A that excites the low-speed breaking electromagnet 34. The excitation power supply 34A receives an input unit 74 that converts AC power received from a commercial power source into an appropriate voltage value, a transformer / rectifier unit 75 that converts the AC power into DC power having a required voltage value, and the DC power. A pattern shaping / output unit 79 for outputting a predetermined excitation current pattern (time change of excitation current), and a control unit 77 for adjusting a timing for outputting a predetermined excitation pattern based on a timing control signal from the control device 600. The By optimizing the number of turns of the exciting coil of the low-speed breaking electromagnet 34, the exciting power supply 34A can be selected as an output voltage and a current that can be easily manufactured, and can be realized with an inexpensive pattern power supply.

  According to the present embodiment, the breaking magnet and the excitation power source constituting the beam blocking device 700 are respectively divided into two for high-speed response and short-time operation at the start of interruption and low-speed response and long-time operation during the subsequent interruption period. Since the functions can be separated, the required performance can be easily achieved, and the design optimized for each operating condition can be realized, so that the apparatus can be reduced in size and cost.

  Further, according to the present embodiment, high-speed beam blocking is possible, and an irradiation beam suitable for particle beam therapy by the spot scanning method can be obtained. In addition, a particle beam therapy system that is small, inexpensive, and easy to adjust can be supplied. As in this embodiment, by arranging the low-speed breaking electromagnet 34 and the high-speed breaking electromagnet 33 as a single unit in the beam cutoff device 700, control and adjustment are facilitated. Even when the low-speed breaking electromagnet 34 and the high-speed breaking electromagnet 33 are arranged in individual devices, the same effect can be obtained by adopting a configuration in which no other device is arranged between them.

[Second Embodiment]
Next, the configuration of the particle beam therapy system according to the second embodiment of the present invention will be described. FIG. 7 is a system configuration diagram showing the overall configuration of the particle beam therapy system according to the present embodiment. Here, only parts different from the system configuration of the first embodiment will be described.

  In the present embodiment, two breaking electromagnets 33 and 34 are arranged on the entrance side of the deflection electromagnet 31 constituting the beam transport system 300, and a beam dump 35 is arranged on the exit side. Since the deflecting electromagnet 31 can be used as a drift space by this equipment arrangement, a long linear portion for ensuring a drift distance is not required in the beam transport system 300 as in the first embodiment. That is, unnecessary beam components can be sufficiently separated and discarded without extending the straight line drift distance. Further, since it is not necessary to extend the straight part drift distance, beam convergence by the quadrupole electromagnet becomes easy, and it is possible to avoid difficulty in adjusting the beam transport.

  The operation | movement of the spot scanning method by the particle beam therapy system of the 2nd Embodiment of this invention is demonstrated. FIG. 8 is a timing chart showing the operation of the spot scanning method by the particle beam therapy system of this embodiment. Here, only parts different from the operation of the first embodiment will be described. In the present embodiment, as illustrated in FIG. 8E, when the low-speed breaking electromagnet 34 is excited, the charged particle beam passes through the beam trajectory of the beam transport system 300 and is supplied to the irradiation device 500. On the other hand, when the breaking electromagnets 33 and 34 are not excited, the charged particle beam passing through the beam trajectory in the beam transport system 300 is deflected from the beam trajectory and collides with the beam dump 35 and is discarded. That is, the operation logic is such that the irradiation beam can be turned on while the low-speed breaking electromagnet is excited. In the present embodiment, since the irradiation beam is automatically turned off in the event of equipment failure, a highly safe system can be constructed. In addition, as shown in FIG. 8D, the high-speed breaking magnet is excited at the opposite polarity to the low-speed breaking magnet at the start of beam breaking, and the falling time of the excitation current of the low-speed breaking magnet is effectively shortened so that the high-speed beam breaking is performed. Is realized. Since the irradiation beam is turned on while the low-speed breaking electromagnet is excited, the installation position and deflection angle of the deflection electromagnet 31 immediately downstream thereof are determined in consideration of the deflection angle of the low-speed breaking electromagnet. Of course, in the present embodiment, it is also possible to turn off the irradiation beam by exciting the two breaking electromagnets in the same operation logic as in the first embodiment. The configuration of the charged particle beam extraction method, irradiation device, breaker magnet, and excitation power source of this embodiment is the same as that of the first embodiment and is as shown in FIGS.

  According to the present embodiment, the same effect as in the first embodiment can be obtained.

  Further, according to the present embodiment, since the deflection electromagnet of the beam transport system 300 can be used as the drift space, unnecessary beam components can be sufficiently separated and discarded without extending the straight line drift distance. Furthermore, since it is not necessary to extend the straight part drift distance, the beam convergence by the quadrupole electromagnet becomes easy, and the difficulty in adjusting the beam transport can be avoided.

[Third Embodiment]
Next, the configuration and operation method of the particle beam therapy system according to the third embodiment of the present invention will be described. FIG. 9 is a system configuration diagram showing the overall configuration of the particle beam therapy system according to the present embodiment. Here, only the parts different from the system configuration and operation method of the first embodiment will be described.

  In this embodiment, a cyclotron 800 is used as an accelerator for accelerating a charged particle beam. The cyclotron 800 includes an ion source 81 that generates a charged particle beam, an acceleration cavity 82 that accelerates the charged particle beam every revolution, a deflecting electromagnet 83 that deflects the charged particle beam and makes it spiral, and an outermost periphery. It comprises an output deflection device 84 that emits a charged particle beam that has reached a predetermined energy.

  In the cyclotron 800, the output beam is turned ON / OFF by applying a high voltage ON / OFF applied to the ion source 81. More specifically, any one of an arc voltage for generating plasma that is a source of the charged particle beam, an acceleration voltage for extracting the charged particle beam from the plasma, and a deflection voltage applied to the charged particle beam immediately after extraction is turned ON / OFF. Thus, the outgoing beam can be turned ON / OFF. However, in any case, ON / OFF is not possible instantaneously, and a delay corresponding to the response of the high voltage power supply and the circulation time in the cyclotron occurs.

  FIG. 10 is a timing chart showing the operation of the spot scanning method by the particle beam therapy system of this embodiment. The difference from FIG. 4 in the case of the first embodiment is that the high frequency power applied to the extraction device 26 is turned on / off in the synchrotron 200, whereas the high voltage applied to the ion source 81 is turned on / off in the cyclotron 800. It is a point to turn off. In either case, since it takes time until the outgoing beam is interrupted, irradiation during this delay time (delayed irradiation) occurs. The configuration and operation method of the beam blocking device 700 for reducing the delayed irradiation amount are the same as in the case of the first embodiment (FIGS. 3 to 6), and thus the description thereof is omitted.

  According to the present embodiment, the same effect as in the first embodiment can be obtained.

  In addition, the cyclotron 800 is smaller than the synchrotron 200. On the other hand, if the overall system size is constant, the linear part drift distance of the beam transport system can be increased, so that the required performance of each device of the beam blocking device can be more relaxed. .

[Fourth Embodiment]
Next, the configuration of the particle beam therapy system according to the fourth embodiment of the present invention will be described. FIG. 11 is a system configuration diagram showing the overall configuration of the particle beam therapy system according to the present embodiment. In the present embodiment, a cyclotron 800 is used as an accelerator for accelerating a charged particle beam, as in the third embodiment, and, as in the second embodiment, the beam blocking device 700 includes a beam transport system 300. In this configuration, two breaking electromagnets 33 and 34 are disposed on the entrance side of the deflection electromagnet 31 and a beam dump 35 is disposed on the exit side.

  FIG. 12 is a timing chart showing the operation of the spot scanning method by the particle beam therapy system of this embodiment. The difference from FIG. 8 in the case of the second embodiment is that the high frequency power applied to the extraction device 26 is turned on / off in the synchrotron 200, whereas the high voltage applied to the ion source 81 is turned on / off in the cyclotron 800. It is a point to turn off.

  According to the present embodiment, the same effect as in the first embodiment can be obtained.

  Further, in the case of the present embodiment, the irradiation beam suitable for the particle beam therapy by the spot scanning method can be obtained after achieving the miniaturization of the entire system.

[Fifth Embodiment]
Finally, the configuration of the particle beam therapy system according to the fifth embodiment of the present invention will be described. FIG. 13 is a system configuration diagram showing the overall configuration of the particle beam therapy system according to the present embodiment. Unlike the other embodiments, in this embodiment, one of the two breaking electromagnets is disposed on the entrance side of the deflection electromagnet 31 of the beam transport system 300 and the other is disposed on the linear portion of the beam transport system 300. In FIG. 13, the high-speed breaking electromagnet 33 is arranged in the straight line portion, but the reverse may be possible. In this embodiment, the cyclotron 800 is used as an accelerator, but the synchrotron 200 may be used.

  The operation of the spot scanning method by the particle beam therapy system of this embodiment is the same as that of the other embodiments, and the timing chart showing the operation is as described with reference to FIG. 4, FIG. 8, FIG. This embodiment can be applied when it is difficult to arrange two breaking electromagnets close to each other due to the design of the beam transport system.

  As described above in Embodiments 1 to 5, according to the present invention, a high-speed beam blocking is possible, an irradiation beam suitable for particle beam therapy by the spot scanning method is obtained, and a particle beam that is small, inexpensive, and easy to adjust A treatment system can be supplied. In particular, since unnecessary dose administration can be avoided reliably even when irradiating a remote spot at a position where the irradiation spot is remote, high-precision treatment irradiation corresponding to a complicated affected part shape can be easily realized.

  In addition, although the beam cutoff apparatus 700 of Embodiments 1-5 is functionally separated into two, it is not limited to two, You may have a some interruption | blocking electromagnet and excitation power supply.

  The present invention irradiates a target with high-accuracy and desired intensity distribution with a high-energy charged particle beam accelerated by an accelerator such as a synchrotron or a cyclotron in addition to a particle beam therapy system for cancer treatment or the like. Applicable to physics research with necessity.

1 is a system configuration diagram showing a configuration of a particle beam therapy system according to a first embodiment of the present invention. It is explanatory drawing of the extraction method of the charged particle beam from a synchrotron in the particle beam therapy system by the 1st Embodiment of this invention. It is a front view which shows the structure of the irradiation apparatus used for the particle beam therapy system by the 1st Embodiment of this invention. It is a timing chart which shows operation | movement of the spot scanning method in the particle beam therapy system by the 1st Embodiment of this invention. It is sectional drawing which shows the structure of the interruption | blocking electromagnet of the beam interruption apparatus used for the particle beam therapy system by the 1st Embodiment of this invention. It is an apparatus block diagram which shows the structure of the excitation power supply of the beam blocker used for the particle beam therapy system by the 1st Embodiment of this invention. It is a system block diagram which shows the structure of the particle beam therapy system by the 2nd Embodiment of this invention. It is a timing chart which shows operation | movement of the spot scanning method in the particle beam therapy system by the 2nd Embodiment of this invention. It is a system block diagram which shows the structure of the particle beam therapy system by the 3rd Embodiment of this invention. It is a timing chart which shows operation | movement of the spot scanning method in the particle beam therapy system by the 3rd Embodiment of this invention. It is a system block diagram which shows the structure of the particle beam therapy system by the 4th Embodiment of this invention. It is a timing chart which shows the operation | movement of the spot scanning method in the particle beam therapy system by the 4th Embodiment of this invention. It is a system block diagram which shows the structure of the particle beam therapy system by the 5th Embodiment of this invention. It is a system block diagram which shows the structure of the particle beam therapy system by a prior art. It is a timing chart which shows operation | movement of the spot scanning method in the particle beam therapy system by a prior art.

Explanation of symbols

11 Pre-accelerator 21, 31, 83 Bending electromagnet 22, 32 Converging / diverging quadrupole electromagnet 23 Hexapole electromagnet 24 Incident device 25, 82 Acceleration cavity 26 Ejecting device 26A, 33A, 34A, 81A, 500A Power supply 27, 84 Device 33 High-speed breaking electromagnet 34 Low-speed breaking electromagnet 35 Beam dump 41 Patient 42 Affected part 51 Scanning magnet 52 Beam monitor 71 Magnetic body core 72 Beam duct 73 Excitation coil 74 Input part 75 Transformer / rectifier part 76 Pulse shaping part 77 Control part 78 Output part 79 Pattern shaping / output unit 81 Ion source 100 Particle beam therapy system 200 Synchrotron 300 Beam transport system 400 Treatment room 500 Irradiation device 600 Control device 700 Beam blocking device 800 Cyclotron

Claims (5)

An acceleration device for accelerating and emitting a charged particle beam to a predetermined energy;
An irradiation device for emitting the charged particle beam to an irradiation target;
A beam transport system for guiding the charged particle beam emitted from the acceleration device to the irradiation device;
A beam blocking device installed in the beam transport system and blocking the supply of the charged particle beam to the irradiation device;
The beam blocking device, possess a first shielding magnet for deflecting the charged particle beam passing through the beam transport system, a second shielding magnet to the first shielding magnet and the response speed is different,
By exciting the first breaker magnet having a response speed faster than that of the second breaker magnet at the rise or fall time of the excitation current of the second breaker magnet, the charged particle beam to the irradiation device is excited. A particle beam therapy system characterized by cutting off the supply . The beam blocking device is
The first and second breaking electromagnets installed on the entrance side of a deflection electromagnet constituting the beam transport system ;
The particle beam therapy system according to claim 1, further comprising a beam dump installed on an exit side of the deflection electromagnet .   The particle beam therapy system according to claim 2, wherein the beam blocking device deflects a charged particle beam by the blocking electromagnet and extinguishes the deflected charged particle beam by the beam dump. The first breaking electromagnet and the second breaking electromagnet generate a dipole magnetic field component having substantially opposite polarity, and deflect the charged particle beam guided to the beam transport system in a reverse direction. The particle beam therapy system according to claim 1 or 2 . The beam blocking device excites the second blocking magnet to deflect the charged particle beam, supplies the deflected charged particle beam to the irradiation device, stops excitation of the second blocking magnet, and 3. The particle beam according to claim 1, wherein the supply of the charged particle beam to the irradiation device is interrupted by exciting the first interrupting magnet having a response speed higher than that of the two interrupting magnets. Treatment system.

Images