JP6552859B2 - Charged particle beam therapy system - Google Patents

Description

  The present invention relates to a charged particle beam therapy system.

  Conventionally, as a charged particle beam therapy apparatus that performs treatment by irradiating an irradiated body with a charged particle beam, for example, a charged particle beam therapy apparatus described in Patent Document 1 is known. In this charged particle beam therapy system, the energy of the beam emitted from the cyclotron 2 (accelerator) is adjusted (decreased) by the degrader 10 to adjust the beam range (the arrival position of the beam in the patient). .

International Publication No.2012 / 090614

  However, in order to adjust the beam range with high accuracy, it is necessary to adjust the energy of the beam with high accuracy. For example, the energy output from the accelerator may slightly fluctuate due to maintenance of the accelerator or the like. Then, the range of the beam changes in response to the change, so it is desirable to suppress such a change in the range. Therefore, the present invention has been made to solve such a problem, and an object of the present invention is to provide a charged particle beam therapeutic apparatus capable of adjusting the range of a beam with high accuracy.

  The charged particle beam therapy system according to the present invention comprises an accelerator that accelerates charged particles to emit charged particle beams, an irradiation unit that irradiates the charged particle beam to the irradiation target, and energy of the charged particle beams irradiated from the irradiation unit. And an energy fluctuation adjusting unit for adjusting the fluctuation of the energy of the charged particle beam emitted from the accelerator based on the measured value of the energy measured by the energy measuring unit.

  The charged particle beam therapy system of the present invention further includes a range adjusting unit that adjusts the range of the charged particle beam by reducing the energy of the charged particle beam, and the energy fluctuation adjusting unit is more than the range adjusting unit. It may be provided upstream.

  In addition, the energy fluctuation adjusting unit causes the charged particle beam emitted from the accelerator to pass through and reduce the energy of the charged particle beam, and the respective energy reduced portions on the passage path of the charged particle beam. It is good also as having a drive part made to move by the position of and the retracted position evacuated from the passage route.

  The charged particle beam therapy system according to the present invention further includes a range adjusting unit that adjusts a range of the charged particle beam by reducing the energy of the charged particle beam, and the energy fluctuation adjusting unit is charged by the charge emitted from the accelerator. A plurality of energy lowering portions that pass the particle beam and reduce the energy of the charged particle beam, each energy lowering portion, a position on the passage path of the charged particle beam, a retreat position that is retracted from the passage path, The energy reducing portion may have a thickness smaller than the minimum thickness of the attenuating material provided in the range adjusting portion.

  According to the present invention, it is possible to provide a charged particle beam therapy system capable of adjusting the range of a beam with high accuracy.

FIG. 1 is a schematic view showing an embodiment of a charged particle beam irradiation apparatus according to the present invention. FIG. 2 is a block configuration diagram illustrating functions of the control unit. FIG. 3 is a flowchart showing the processing contents in the parameter preparation stage. FIG. 4 is a flowchart showing the processing contents at the time of layer switching. FIG. 5 is a diagram showing parameter setting and a charged particle beam irradiation image. FIG. 6 is a cross-sectional view showing the energy fluctuation adjusting unit.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The terms "upstream" and "downstream" mean upstream (accelerator side) and downstream (patient side) of the emitted charged particle beam, respectively.

  As shown in FIG. 1, the charged particle beam treatment apparatus 1 is a device used for cancer treatment by radiation therapy, etc., and includes an accelerator 11 that accelerates charged particles to emit charged particle beams, and charged particle beams. An irradiation nozzle 12 (irradiation unit) for irradiating an object to be irradiated, a beam transportation line 13 (transport line) for transporting charged particle beams emitted from the accelerator 11 to the irradiation nozzle 12, and a beam transportation line 13 Degrader 18 that adjusts the range of charged particle beam by reducing energy of particle beam, a plurality of electromagnets 25 provided in beam transport line 13, and an electromagnet power source provided corresponding to each of a plurality of electromagnets 25 27 and a control unit 30 that controls the entire charged particle beam therapy system 1. In this embodiment, a cyclotron is used as the accelerator 11. However, the present invention is not limited to this, and other generation sources that generate charged particle beams such as synchroton, synchrocycloton, linac, and the like may be used.

  In the charged particle beam therapy apparatus 1, irradiation of the charged particle beam emitted from the accelerator 11 is performed on the tumor (irradiated body) of the patient P on the treatment table 22. A charged particle beam is one obtained by accelerating a charged particle at a high speed, such as a proton beam or a heavy particle (heavy ion) beam. The charged particle beam treatment apparatus 1 according to the present embodiment performs irradiation of a charged particle beam by a so-called scanning method, virtually divides (slices) an irradiated body in a depth direction, and a slice plane (layer). Each time, the charged particle beam is irradiated to the irradiation range on the layer (see, for example, FIG. 5).

  In addition, as an irradiation method by a scanning method, there are spot type scanning irradiation and raster type scanning irradiation, for example. The spot type scanning irradiation is the irradiation range, and once irradiation of one spot is completed, the irradiation of the beam (charged particle beam) is stopped once, and irradiation of the next spot is made after the irradiation preparation for the next spot is ready. It is a method to do. On the other hand, the raster scanning irradiation is a method in which the irradiation of the same layer is continuously performed without stopping the irradiation halfway. As described above, raster-type scanning irradiation is such that beam irradiation is continuously performed for the irradiation range of the same layer, so unlike spot-type scanning irradiation, the irradiation range is not composed of a plurality of spots. . Hereinafter, an example in which irradiation is performed by spot scanning irradiation will be described, and the irradiation range on the same layer will be described as being composed of a plurality of spots, but the present invention is not limited to this, and irradiation is performed by raster scanning irradiation. In the case, as described above, the irradiation range may not be composed of spots.

  The irradiation nozzle 12 is attached to the inside of a rotating gantry 23, which can rotate 360 degrees around the treatment table 22, and can be moved by the rotating gantry 23 to an arbitrary rotational position. The irradiation nozzle 12 includes a focusing electromagnet 19 (details will be described later), a scanning electromagnet 21 and a vacuum duct 28. The scanning electromagnet 21 is provided in the irradiation nozzle 12. The scanning electromagnet 21 scans a charged particle beam in the X direction on a plane that intersects the charged particle beam irradiation direction, and a Y direction that intersects the X direction on a plane that intersects the charged particle beam irradiation direction. And a Y-direction scanning electromagnet that scans the charged particle beam. Further, since the charged particle beam scanned by the scanning electromagnet 21 is deflected in the X direction and / or the Y direction, the diameter of the vacuum duct 28 on the downstream side of the scanning electromagnet is enlarged toward the downstream side.

  The beam transport line 13 has a vacuum duct 14 through which a charged particle beam passes. The inside of the vacuum duct 14 is maintained in a vacuum state, which suppresses scattering of charged particles constituting the charged particle beam during transport by air or the like.

  The beam transport line 13 includes an ESS (Energy Selection System) 15 that selectively takes out a charged particle beam having an energy width narrower than a predetermined energy width from a charged particle beam having a predetermined energy width emitted from the accelerator 11. , A BTS (Beam Transport System) 16 that transports a charged particle beam having an energy width selected by the ESS 15 while maintaining energy, and a GTS (Gantry) that transports a charged particle beam from the BTS 16 toward the rotating gantry 23. And Transport System) 17.

  The degrader (range adjustment unit) 18 adjusts the range of the charged particle beam by reducing the energy of the charged particle beam passing therethrough. Since the depth from the patient's body surface to the tumor to be irradiated varies from patient to patient, when irradiating the charged particle beam to the patient, it is necessary to adjust the range which is the arrival depth of the charged particle beam is there. The degrader 18 adjusts the energy of the charged particle beam emitted from the accelerator 11 with a constant energy (adjusts the amount of energy reduction), thereby applying the charged particle beam to the irradiated object at a predetermined depth in the patient body. Adjust to reach properly. Such energy adjustment of the charged particle beam by the degrader 18 is performed for each layer obtained by slicing the irradiated object. For example, the degrader 18 has a damping material that reduces the energy of the passing charged particle beam, and adjusts the amount of reduction of the charged particle beam energy by adjusting the thickness of the damping material through which the charged particle beam passes. Further, as a method of adjusting the thickness of the damping material, the thickness of the damping material may be linearly or stepwise changed, and a portion having a desired thickness of the damping material may be inserted on the passage of the beam B. . As another method of adjusting the thickness of the attenuation material, a plurality of attenuation materials may be provided to adjust the number of attenuation materials that allow the charged particle beam to pass therethrough.

  A plurality of electromagnets 25 are provided in the beam transport line 13, and the charged particle beam is adjusted so that the charged particle beam can be transported in the beam transport line 13 by the magnetic field. As the electromagnet 25, a converging electromagnet 19 for converging the beam diameter of the charged particle beam being transported and a deflection electromagnet 20 for deflecting the charged particle beam are employed. Hereinafter, the converging electromagnet 19 and the deflecting electromagnet 20 may be referred to as an electromagnet 25 without distinction. Further, a plurality of electromagnets 25 are provided downstream of the degrader 18 of at least the beam transport line 13. However, in the present embodiment, the electromagnet 25 is also provided upstream of the degrader 18. Here, a converging electromagnet 19 as the electromagnet 25 is also provided on the upstream side of the degrader 18 in order to converge the beam diameter of the charged particle beam before energy adjustment by the degrader 18. The total number of the electromagnets 25 can be flexibly changed according to the length of the beam transport line 13 or the like, and is, for example, a number of about 10 to 40. Although only a part of the electromagnet power supply 27 is shown in FIG. 1, in practice, the same number as the number of electromagnets 25 is provided.

  The positions of the degrader 18 and the electromagnet 25 in the beam transport line 13 are not particularly limited, but in the present embodiment, the ESS 15 is provided with a degrader 18, a converging electromagnet 19, and a deflection electromagnet 20. The BTS 16 is provided with a converging electromagnet 19, and the GTS 17 is provided with a converging electromagnet 19 and a deflection electromagnet 20. The degrader 18 is provided in the ESS 15 between the accelerator 11 and the rotating gantry 23 as described above. More specifically, the degrader 18 is provided in the accelerator 11 side (upstream side) of the rotating gantry 23 in the ESS 15. It is done.

  The electromagnet power supply 27 generates a magnetic field of the electromagnet 25 by supplying a current to the corresponding electromagnet 25. The electromagnet power supply 27 can set the strength of the magnetic field of the corresponding electromagnet 25 by adjusting the current supplied to the corresponding electromagnet 25. The electromagnet power source 27 adjusts the current supplied to the electromagnet 25 in accordance with a signal from the control unit 30 (details will be described later). The electromagnet power supply 27 is provided so as to correspond to each electromagnet 25 one to one. That is, the same number of electromagnet power supplies 27 as the number of electromagnets 25 are provided.

  The relationship between the depth of each layer of the object to be irradiated and the current supplied to the electromagnet 25 is as follows. That is, the energy of the charged particle beam necessary for irradiating the charged particle beam to each layer is determined from the depth of each layer, and the amount of energy adjustment by the degrader 18 is determined. Here, when the energy of the charged particle beam changes, the strength of the magnetic field required to deflect and converge the charged particle beam also changes. Therefore, the current supplied to the electromagnet 25 is determined so that the strength of the magnetic field of the electromagnet 25 becomes a strength corresponding to the amount of energy adjustment by the degrader 18.

  Next, details of the control unit 30 and the electromagnet power supply 27 will be described with reference to FIG. Although only three electromagnet power supplies 27 are shown in FIG. 2, actually, the corresponding electromagnet power supplies 27 are provided as many as the number of the electromagnets 25 provided in the charged particle beam therapy system 1. Further, although the electromagnet 25 is not illustrated in FIG. 2, the electromagnet 25 electrically connected to the electromagnet power source 27 is actually provided.

  The control unit 30 controls the irradiation of the charged particle beam emitted from the accelerator 11 to the irradiated object. The control unit 30 has a main control unit 31, a beam control unit 32, an ESS control unit 33, a BTS control unit 34, a GTS control unit 35, a scanning control unit 36, and a layer control unit 37. ing.

  The main control unit 31 controls the beam control unit 32 and the scanning control unit 36. Specifically, the main control unit 31 transmits the process start signal to the beam control unit 32 and the scanning control unit 36 to start the process, and transmits the process end signal to end the process.

  The beam control unit 32 controls each function so that the charged particle beam can be irradiated to the irradiation target. Specifically, the beam control unit 32 transmits a process start signal to the cycloton control unit (not shown) in response to the process start signal from the main control unit 31, and the accelerator 11 receives the charged particle beam. Let the light exit. Further, the beam control unit 32 transmits a process start signal to the ESS control unit 33, the BTS control unit 34, and the GTS control unit 35 in accordance with the process start signal from the main control unit 31.

  The ESS control unit 33 turns on the electromagnet power source 27 corresponding to the electromagnet 25 provided in the ESS 15 in response to the processing start signal from the beam control unit 32. Similarly, in response to the processing start signal from the beam control unit 32, the BTS control unit 34 turns on the electromagnet power supply 27 corresponding to the electromagnet 25 provided in the BTS 16. Similarly, in response to the process start signal from the beam control unit 32, the GTS control unit 35 turns on the power supply of the electromagnet power supply 27 corresponding to the electromagnet 25 provided in the GTS 17. The charged particle beam emitted from the accelerator 11 is covered by the control of the accelerator 11 by the beam control unit 32 and the control of the electromagnet power source 27 by the ESS control unit 33, the BTS control unit 34, and the GTS control unit 35. The irradiation body can be irradiated, and thereafter, the control by the scanning control unit 36 is performed.

  The scanning control unit 36 controls scanning (scanning) of the charged particle beam to the irradiation object. The scanning control unit 36 transmits an irradiation start signal to the scanning electromagnet 21 in response to the processing start signal from the main control unit 31, and causes the scanning electromagnet 21 to irradiate a plurality of irradiation spots on the same layer. . Information regarding the irradiation spot in each layer is stored in the scanning control unit 36 in advance. Further, when the irradiation of all the spots of one layer by the scanning electromagnet 21 is completed, the scanning control unit 36 transmits a layer switching signal to the layer control unit 37. The layer switching signal includes information (for example, the second layer, etc.) for specifying the layer after switching.

  The charged particle beam irradiation image of the scanning electromagnet 21 according to the control of the scanning control unit 36 will be described with reference to FIGS. 5 (b) and 5 (c). FIG. 5 (b) shows the irradiation target virtually sliced into a plurality of layers in the depth direction, and FIG. 5 (c) shows the charged particle beam in one layer viewed from the irradiation direction of the charged particle beam. Scanned images are shown respectively.

  As shown in FIG. 5 (b), the irradiated object is virtually sliced into a plurality of layers in the depth direction, and in this example, a deep layer (the range of the charged particle beam irradiation beam B is long). Layer L1, layer L2,... Layer Ln-1, layer Ln, layer Ln + 1,... Layer LN-1, layer LN and layer L are virtually sliced in this order. Further, as shown in FIG. 5C, the irradiation beam B is irradiated to a plurality of irradiation spots on the layer Ln while drawing the beam trajectory TL. That is, the irradiation nozzle 12 controlled by the scanning control unit 36 moves on the beam trajectory TL.

  Returning to FIG. 2, the layer control unit 37 performs layer switching-related processing in accordance with the layer switching signal from the scanning control unit 36. The layer switching-related process is a degrader setting process for changing the energy adjustment amount of the degrader 18 and an electromagnet setting process in which the parameters of the electromagnet 25 are set in accordance with the energy adjustment amount of the degrader 18 after the degrader setting process. The parameter of the electromagnet 25 is a target value of the current supplied to the electromagnet 25.

  Here, in charged particle beam therapy, when treating a certain patient, it is planned how to irradiate the charged particle beam to that patient (treatment plan). The treatment plan data determined at the time of the treatment plan is transmitted from the treatment planning apparatus (not shown) to the layer control unit 37 of the control unit 30 before the treatment is performed, and is stored in the layer control unit 37. In the treatment plan data, the energy adjustment amount of the degrader 18 for irradiating each layer of the irradiated body with the charged particle beam, and the electromagnet 25 for irradiating all the layers according to the energy adjustment amount of the degrader 18 Parameters etc. are included.

  The layer control unit 37 first performs a degrader setting process as a layer switching related process. As described above, the layer control unit 37 stores in advance the energy adjustment amount of the degrader 18 for irradiating each layer of the irradiated object with the charged particle beam. Then, in accordance with the layer switching signal from the scanning control unit 36, the layer control unit 37 sets the energy adjustment amount of the degrader 18 to a value according to the layer after switching.

  The layer control unit 37 performs an electromagnet setting process after the degrader setting process. Specifically, the layer control unit 37 transmits layer switching signals simultaneously to the respective electromagnet power supplies 27 so that the parameters of the electromagnets 25 correspond to the energy adjustment amount of the degrader 18 after the degrader setting process. Do. Here, the layer switching signal transmitted from the layer control unit 37 to the electromagnet power source 27 simply includes information for specifying the layer after switching, and the parameters (degrader) of the electromagnet 25 corresponding to the layer after switching. The parameters of the electromagnet 25 according to the energy adjustment amount of the degrader 18 after the setting process are not included. The parameter change of the electromagnet 25 is performed by an electromagnet power source 27. As a premise, the layer control unit 37 sets the parameters of the electromagnet 25 for irradiating all the layers according to the energy adjustment amount of the degrader 18 in the treatment plan data described above before the irradiation is started (to the layers). (Not immediately before the irradiation (switching) but before the treatment is started).

  The electromagnet power supply 27 responds to the layer switching signal received from the layer control unit 37, and the parameters of the electromagnet 25 corresponding to the switched layer (the parameters of the electromagnet 25 according to the energy adjustment amount of the degrader 18 after the degrader setting process). Set Specifically, the electromagnet power supply 27 has a storage unit 27a that stores parameters of the electromagnet 25 corresponding to each layer, and is included in the layer switching signal when the layer switching signal is received from the layer control unit 37. Set parameters corresponding to the switched layer. As a result, a current corresponding to the layer after switching is supplied to the electromagnet 25.

  The parameter setting by the electromagnet power supply 27 will be described with reference to FIG. As shown in FIG. 5A, all the electromagnet power supplies 27 include parameters D1 to D1 of the electromagnet 25 corresponding to each layer of the irradiated object, specifically, the layers L1 to LN (see FIG. 5B). DN is stored. Then, the electromagnet power source 27 sets the parameter Dn according to information (L = n) that identifies the layer after switching included in the layer switching signal SG transmitted from the layer control unit 37.

  The layer control unit 37 determines that the parameter setting of the electromagnet power source 27 is completed after a predetermined time (for example, 50 msec to 200 msec) has elapsed after transmitting the layer switching signal to the electromagnet power source 27 and switches to the scanning control unit 36. Send a completion signal. Then, the scanning control unit 36 transmits an irradiation start signal to the scanning electromagnet 21 in response to the switching completion signal.

  Next, processing for preparing (storing) parameters of the electromagnet 25 in the storage unit 27a of the electromagnet power supply 27 will be described with reference to FIG.

  First, the layer control unit 37 reads a scanning data table from the treatment planning apparatus (S101). The parameters of the electromagnet 25 for each layer are set in advance in consideration of the energy of the charged particle beam according to the object to be irradiated.

  Subsequently, the layer control unit 37 selects a parameter of the electromagnet 25 as transmission information for the electromagnet power supply 27 (S102). The parameters of the electromagnet 25 are managed for each layer.

  Subsequently, the parameter of the electromagnet 25 is transmitted to the electromagnet power source 27 by the layer control unit 37 (S103). As parameters, for example, parameters of the electromagnets 25 of all layers are put together and sequentially transmitted to the respective electromagnet power supplies 27.

  Finally, the parameters of the electromagnets 25 of all layers transmitted from the layer control unit 37 are stored and stored in the storage unit 27a of the electromagnet power supply 27. The above is the process of storing the parameters of the electromagnet 25 in the storage unit 27a. When the storage process is completed, the parameter setting process of the electromagnet 25 in which the layer control unit 37 and the electromagnet power supply 27 cooperate with each other at the time of layer switching becomes possible.

  Next, parameter setting processing at the time of layer switching will be described with reference to FIGS. As a premise of performing the process, parameters of the electromagnet 25 are prepared (stored) in the storage unit 27a of the electromagnet power supply 27, and control of the accelerator 11 by the beam control unit 32, the ESS control unit 33, and the BTS control unit 34 and the control of the electromagnet power supply 27 by the GTS control unit 35, the charged particle beam emitted from the accelerator 11 needs to be able to be irradiated to the irradiated object.

  An example in which charged particle beams are applied to the layers L1 to LN of the irradiated object shown in FIG. As a premise of the process described below, setting for irradiating the charged particle beam to the layer L1 which is the deepest layer of the irradiated body is performed. Specifically, the parameter D1 of the electromagnet 25 corresponding to the layer L1 is set by the electromagnet power supply 27.

  First, based on the irradiation start signal from the scanning controller 36, the scanning electromagnet 21 irradiates all the irradiation spots on the layer L1 of the irradiated body with charged particle beams (S201). When the irradiation to all irradiation spots of the layer L1 is completed, the scanning control unit 36 transmits a layer switching signal SG to the layer control unit 37 (S202). The layer switching signal SG includes information (L = 2) for specifying the layer L2 after switching.

  Subsequently, based on the layer switching signal SG from the scanning control unit 36, the layer control unit 37 changes the energy adjustment amount of the degrader 18 (S203). Specifically, the layer control unit 37 irradiates the charged particle beam to the information (L = 2) specifying the switched layer L2 included in the layer switching signal SG and the layer stored in advance. The energy adjustment amount of the degrader 18 is changed to a value corresponding to the layer L2 after switching, based on the information on the energy adjustment amount of the degrader 18 to be performed.

  Subsequently, the layer control unit 37 transmits a layer switching signal SG to each electromagnet power source 27 (S204). The layer switching signal SG transmitted to the electromagnet power supply 27 by the layer control unit 37 simply includes information (L = 2) for specifying the layer L2 after switching, and corresponds to the layer L2 after switching. The parameter D2 of the electromagnet 25 to be performed (the parameter D2 of the electromagnet 25 according to the energy adjustment amount of the degrader 18 after the degrader setting process) is not included.

  Subsequently, on the basis of the layer switching signal SG from the layer control unit 37, the electromagnet power source 27 corresponds to the parameter D2 of the electromagnet 25 corresponding to the switched layer L2 (according to the energy adjustment amount of the degrader 18 after the degrader setting process). The parameter D2) of the electromagnet 25 is set (S205). Thereby, the current corresponding to the layer L2 after switching is supplied to the electromagnet 25, and appropriate irradiation of the charged particle beam can be performed on the layer L2 after switching.

  Finally, the layer control unit 37 transmits a switching completion signal to the scanning control unit 36 (S206). The above is the parameter setting process at the time of layer switching. In response to the transmission of the switching completion signal by the layer control unit 37, the scanning control unit 36 transmits an irradiation start signal to the scanning electromagnet 21. By repeating such processes of S201 to S206, parameter setting process at the time of switching to each layer is performed. That is, for example, when switching from the layer Ln-1 to the layer Ln, the parameters of the layer Ln after switching are set by performing the above-described processing of S201 to S206. Finally, when the process of S201 for the layer LN (irradiation to all spots) is completed, the scanning control unit 36 sends an irradiation completion signal to the main control unit 31 indicating that irradiation of all layers of the irradiated object has been completed. The radiotherapy for the patient is completed.

  Further, in the charged particle beam therapy system 1 according to the present embodiment, the layer control unit 37 identifies the switched layer with respect to the electromagnet power supply 27 at the time of switching the layer of the irradiated body that emits the charged particle beam. A layer switching signal containing information is transmitted.

  When switching the layer of the irradiation object in the charged particle beam therapy apparatus, the energy of the charged particle beam is changed to one corresponding to the layer after switching, and the charged particle beam after the energy change is changed to the layer after switching It is necessary to change the parameters of the electromagnet (such as the current supplied to the electromagnet) in order to properly irradiate. Conventionally, when switching the layer of an object to be irradiated, a parameter related to the layer after switching of the corresponding electromagnet is transmitted to each electromagnet power source from the device that controls the electromagnet power source each time. The parameters of the electromagnet are different values for each electromagnet, and since the parameters include multiple information such as the current supplied to the electromagnet, data communication between the device controlling the electromagnet power supply and each electromagnet power supply Took time (for example, about 1 second). This took time to switch layers.

  In this regard, in the charged particle beam therapy system 1 according to the present embodiment, the electromagnet power source 27 includes a storage unit 27a that stores parameters of the electromagnet 25 for each layer in the irradiated body. Then, as described above, at the time of layer switching, the layer control unit 37 transmits, to the electromagnet power supply 27, a layer switching signal including information for specifying the layer after switching. Therefore, the electromagnet power supply 27 can set the parameter of the electromagnet 25 of the layer after switching stored in the storage unit 27a based on the layer switching signal transmitted from the layer control unit 37. In this way, by storing the parameters of the electromagnets 25 of each layer in the storage unit 27a of the electromagnet power supply 27, the device (layer control unit 37) that controls the electromagnet power supply to the electromagnet power supply 27 at the time of layer switching. It is not necessary to transmit the parameters themselves of each layer, and it is sufficient to simply transmit a signal (a layer switching signal including information specifying the layer after switching) to indicate the switching timing. As a result, the data communication time between the layer control unit 37 and each electromagnet power supply 27 can be significantly shortened (for example, 10 msec). Thereby, the layer switching time can be shortened and the irradiation time can be shortened.

  Further, as described above, the layer switching signal transmitted from the layer control unit 37 to the electromagnet power supply 27 includes information for specifying a layer. Then, the electromagnet power source 27 sets the parameters of the electromagnet 25 corresponding to the identified layer from the information identifying the layer included in the layer switching signal and the parameters of the electromagnet 25 corresponding to each layer stored in the storage unit 27a. Do. As described above, when the layer switching signal includes the information for specifying the layer, the electromagnet power supply 27 can uniquely specify the parameter of the layer to be set after the switching, and the layer switching process becomes easy.

  Further, since the irradiation nozzle 12 is attached to the rotating gantry 23 that can rotate around the irradiated body, the charged particle beam can be irradiated to the irradiated body from multiple directions. Thereby, irradiation of the charged particle beam to the irradiation object can be performed more effectively.

  In addition, since the degrader 18 is provided between the accelerator 11 and the rotating gantry 23, the energy of the charged particle beam emitted from the accelerator 11 can be reliably adjusted before the irradiated object is irradiated. .

  Here, the degrader 18 reduces the energy of the charged particle beam by receiving the charged particle beam. The degrader 18 emits gamma rays and neutron rays by being highly activated. When arranged close to (i.e., the irradiated object side), the radiation dose in the configuration related to irradiation may increase on the irradiated object side. In this respect, the degrader 18 is provided at a position closer to the accelerator 11 than the rotating gantry 23, and adjusts energy at a position sufficiently separated from the irradiated body. Can be suppressed from becoming high.

  By the way, in the charged particle beam therapy system 1 of this type, when scanning the irradiation beam B, in order to accurately apply the energy of the beam to the targeted depth in the patient body, the beam range (the beam distance in the patient body It is desirable to adjust the arrival position) with high accuracy. In order to adjust the beam range with high accuracy, it is necessary to adjust the energy of the beam with high accuracy.

  For example, when maintenance of the accelerator 11 (cyclotron) is performed, energy output from the accelerator 11 may fluctuate due to a change in position associated with replacement of a deflector electrode, a center electrode, or the like provided in the accelerator 11. . After maintenance, since the beam range fluctuates in response to the above-mentioned energy fluctuation, it is desirable to suppress the beam fluctuation in the beam corresponding to the above fluctuation. Here, although the degrader 18 adjusts the range for scanning the beam B, the accuracy of the energy adjustment of the beam is relatively coarse, and the energy of the beam caused by the fluctuation of the accelerator 11 is finely adjusted. Not suitable for.

  Therefore, as shown in FIG. 1, the charged particle beam therapy system 1 is measured by a water phantom 61 (energy measurement unit) for measuring the energy of the beam irradiated from the irradiation nozzle 12 and the water phantom 61. And an energy fluctuation adjusting unit 63 that adjusts fluctuation of the energy of the beam emitted from the accelerator 11 based on the measured value of energy. The energy fluctuation adjustment unit 63 is disposed immediately upstream of the degrader 18.

  As shown in FIG. 6, the energy fluctuation adjusting unit 63 passes a plurality of energy absorbers (energy reduction portions) 65 for passing the beam B and reducing the energy of the beam B, and the respective energy absorbers 65. A holding unit 67 for holding, a drive unit 69 for reciprocating the holding units 67 independently of one another, and a case 71 for sealing the beam transport line 13 in vacuum and containing the energy absorber 65 Yes. The energy absorber 65 has a width larger than the diameter of the beam B passing through the energy fluctuation adjusting unit 63. The holding part 67 has a holding frame part 67a for holding the energy absorber 65 in the central opening. The driving unit 69 can reciprocate the respective energy absorbers 65 at positions on the passage B of the beam B and at a retracted position retracted from the passage Ba via the holding portions 67. . For example, the drive unit 69 reciprocates each energy absorber 65 in a direction orthogonal to the traveling direction of the beam B. As a mechanism for reciprocating the holding portion 67, for example, a ball screw or the like can be used. As described above, by providing the drive mechanism of the energy absorber 65 with the energy fluctuation adjusting unit 63, there is no need to manually adjust the arrangement of the energy absorber 65, and a high activity region near the energy fluctuation adjusting unit 63 There is no need for an operator to enter.

  With this configuration, the energy fluctuation adjustment unit 63 can insert and extract each energy absorber 65 on the passage B of the beam B, and adjust the number of the energy absorbers 65 disposed in the passage Ba, and the energy fluctuation The energy of the beam B passing through the adjusting unit 63 can be adjusted. That is, the energy fluctuation adjustment unit 63 can adjust the energy of the beam B emitted from the accelerator 11 and irradiated from the irradiation nozzle 12. Note that the energy fluctuation adjusting unit 63 can adjust the energy of the beam B more accurately than the degrader 18. For this reason, as the energy absorber 65, for example, a polyimide film (Kapton Film (registered trademark)) having a uniform thickness of about 100 μm can be employed. In addition, a plurality of energy absorbers 65 having different thicknesses (absorption rates of beams) may be mixed. In this case, the variation of energy fluctuation adjustment can be increased. In the example of FIG. 6, four energy absorbers 65 are provided, but the number of energy absorbers 65 is not limited to four, and may be more or less.

  The adjustment accuracy (minimum adjustment amount) of the energy of the beam B by the energy absorber 65 is higher than the adjustment accuracy (minimum adjustment amount) of the energy of the beam B by the degrader 18, and the energy absorber 65 is higher than that of the degrader 18. The energy of the beam B can be finely adjusted. That is, energy smaller than the minimum attenuation amount of energy by the attenuating material of the degrader 18 can be attenuated by one energy absorber 65. As a configuration for this, for example, the energy absorber 65 has a thickness that is smaller than the minimum thickness of the damping material provided in the degrader 18 (the smallest thickness among the thicknesses that can be used when passing the charged particle beam). Is small (thin). In other words, the thickness of the energy absorber 65 is smaller than the thickness of the thinnest portion of the attenuating material of the degrader 18 whose thickness is linearly or stepwise changed. Further, when the degrader 18 has a configuration in which a plurality of attenuating materials are provided and the number of attenuating materials passing through the charged particle beam is adjusted, the energy is larger than the thickness of the thinnest attenuating material provided in the degrader 18. The thickness of the absorber 65 is small.

  The water phantom 61 is for measuring the dose of the beam B from the irradiation nozzle 12. For example, when the charged particle beam therapy system 1 starts daily operation, the dose of the beam B is measured using the water phantom 61, and the therapy is started when the measured value satisfies a predetermined dose standard. In FIG. 1, the water phantom 61 can be irradiated with the beam B from the irradiation nozzle 12 by exchanging the position with the treatment table 22 or placed on the treatment table 22. Can be measured. In addition, since the method to measure the energy of the beam B irradiated to the water phantom 61 is known, detailed description is abbreviate | omitted. Thus, the water phantom 61 functions as an energy measuring unit that measures the energy of the beam B irradiated from the irradiation nozzle 12. Strictly speaking, the water phantom 61 is not a part of the charged particle beam therapy system 1 and is used as described above only at the time of dose measurement, and is otherwise stored at other places, for example. Moreover, as an energy measurement part, it is not restricted to a water phantom, For example, you may provide dosimeter other than a water phantom in the irradiation nozzle 12. As shown in FIG. For example, an ionization chamber may be provided in the irradiation nozzle 12 as an energy measuring unit.

  Next, an adjustment process for adjusting the energy of the beam B emitted from the accelerator 11 and irradiated from the irradiation nozzle 12 using the energy fluctuation adjusting unit 63 will be described. After maintenance of the accelerator 11, the water phantom 61 is used to measure the energy of the beam B from the irradiation nozzle 12. When the energy measured by the water phantom 61 is higher than the reference energy, the energy absorber that is inserted on the passage path Ba of the beam B in the energy fluctuation adjusting unit 63 in accordance with the energy difference. Increase the number of 65. Thereby, it can adjust so that the energy of the beam B supplied downstream may be made low. In addition, when the energy measured by the water phantom 61 is lower than the reference energy, an energy absorber inserted on the passage path Ba of the beam B in the energy fluctuation adjusting unit 63 in accordance with the energy difference. Reduce the number of 65. Thus, the energy of the beam B supplied downstream can be adjusted to be high. The above-mentioned "reference energy" is, for example, the energy of the beam B from the irradiation nozzle 12 measured before the maintenance of the accelerator 11. The adjustment by the energy fluctuation adjusting unit 63 as described above can offset the influence of the fluctuation of the accelerator 11 caused by, for example, maintenance or the like. As a result, the fluctuation of the energy of the beam irradiated from the irradiation nozzle 12 can be suppressed, and the range of the beam can be adjusted with high accuracy. The adjustment process as described above may be automatically performed by the control device, and the operator issues a command to the control device based on the dose measured by the water phantom 61 to drive the energy fluctuation adjustment unit You may

  In addition, the energy fluctuation adjusting unit 63 may be disposed downstream of the degrader 18. However, in this case, it is also necessary to adjust the electromagnet 25 located upstream of the energy fluctuation adjusting unit 63, which causes the adjustment operation to be complicated. Therefore, the energy fluctuation adjusting unit 63 is preferably arranged as upstream as possible, and preferably arranged upstream of the degrader 18.

  The configuration of the charged particle beam therapy system is not limited to the above-described embodiment, and may be modified within a range not changing the gist described in each claim, or applied to another.

  For example, although the scanning control unit 36 and the layer control unit 37 have been described as separate configurations, they may be one configuration having respective functions. Similarly, although the beam control unit 32 and the scanning control unit 36 have been described as separate configurations, they may be one configuration having each function. Although the layer switching signal transmitted from the layer control unit 37 to the electromagnet power supply 27 has been described as including the information for specifying the layer, the layer switching signal does not necessarily have to include the information for specifying the layer. It may be a signal that indicates the timing of the switching. In this case, the irradiation order of each layer needs to be stored in the storage unit of the electromagnet power supply, and the parameters set by the electromagnet power supply need to be constantly managed. Thereby, even if the layer switching signal is a signal simply indicating the timing of layer switching, the parameters of the electromagnet corresponding to the layer after switching can be specified and set.

  Alternatively, the irradiation nozzle may be fixed and fixed irradiation may be performed without using the rotating gantry 23. Further, instead of the degrader 18, another degrader may be provided at a position closer to the rotating gantry than the accelerator 11 or in the irradiation nozzle 12.

  DESCRIPTION OF SYMBOLS 1 ... Charged particle beam irradiation apparatus, 11 ... Accelerator, 12 ... Irradiation nozzle (irradiation part), 13 ... Beam transport line, 18 ... Degrader (range adjustment part) 61 ... Water phantom (energy measurement part), 63 ... Energy Fluctuation adjustment unit, 65: energy absorber (energy reduction unit) 69: drive unit, P: patient (irradiated body).

Claims (4)

An accelerator that accelerates charged particles and emits charged particle beams;
An irradiation unit for irradiating the charged particle beam to an irradiation object in a patient's body ;
The charged particle beam irradiated from the irradiation unit when the range which is the arrival depth of the charged particle beam from the body surface of the patient can be adjusted by adjusting the energy of the charged particle beam An energy measuring unit that measures energy;
An energy fluctuation adjustment unit that adjusts energy of the charged particle beam irradiated from the irradiation unit based on a measurement value of energy measured by the energy measurement unit;
A range adjusting unit configured to adjust the range of the charged particle beam by reducing the energy of the charged particle beam;
The energy fluctuation adjustment unit
It is provided upstream of the range adjustment unit,
The energy of the charged particle beam can be adjusted with higher accuracy than the range adjusting unit,
The energy measurement unit measures the energy of the charged particle beam after being irradiated from the irradiation unit.
Charged particle beam therapy system. The energy fluctuation adjustment unit
A plurality of energy reduction parts for passing the charged particle beam emitted from the accelerator and reducing the energy of the charged particle beam;
The charged particle beam according to claim 1, further comprising: a drive unit configured to move each of the energy reduction portions at a position on the passage of the charged particle beam and a retracted position retracted from the passage. Treatment device. The energy fluctuation adjustment unit
A plurality of energy reduction parts for passing the charged particle beam emitted from the accelerator and reducing the energy of the charged particle beam;
A driving unit configured to move each of the energy reduction portions at a position on the passage of the charged particle beam and a retracted position retracted from the passage;
The charged particle beam therapy system according to claim 1, wherein the energy reducing portion has a thickness smaller than a minimum thickness of the damping material provided in the range adjusting portion.   The charged particle beam therapy system according to any one of claims 1 to 3, wherein the energy measurement unit is a position of a treatment table or a water phantom installed on the treatment table.

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