JP6286168B2 - Charged particle beam irradiation system and irradiation planning system - Google Patents

Description

    The present invention relates to a charged particle beam irradiation system and an irradiation planning system, and in particular, irradiation for creating irradiation plan information used for a charged particle irradiation system and a charged particle beam irradiation system for irradiating and treating an affected part such as a tumor with a charged particle beam. Regarding planning system.

  As a treatment method for patients such as cancer, a method of irradiating an affected area with a charged particle beam is known. A charged particle beam irradiation system for irradiating a charged particle beam includes a charged particle beam generator, a beam transport system, and an irradiation chamber. In the charged particle beam irradiation system, the charged particle beam accelerated by the charged particle beam generator reaches the irradiation device in the irradiation chamber through the beam transport system, and the lateral spread and energy are adjusted by the irradiation device, so that the patient's body A dose distribution suitable for the shape of the affected area is formed. Patent Document 1 discloses a method of alternately performing irradiation position change by a scanning electromagnet and irradiation of a charged particle beam scattered by a scatterer.

  By the way, when an irradiation target such as an affected part moves by breathing or the like, it becomes difficult to form a dose distribution planned in advance. Therefore, as a method for forming a dose distribution as planned, Patent Document 2 discloses a method called repaint irradiation. Repaint irradiation is a method of forming a dose distribution as planned by irradiating the same position multiple times and averaging.

Japanese Patent No. 3518270 JP 2010-253250 A

  In repaint irradiation, the dose distribution can be made closer to a desired distribution as the number of times of irradiation is increased. However, in the conventional repaint irradiation, there is a problem that the irradiation time becomes longer when the number of repaints is increased.

  The objective of this invention is providing the charged particle beam irradiation system which can form dose distribution as planned, and can shorten irradiation time (treatment time) compared with the conventional repaint irradiation.

  In order to solve the above problems, the present invention provides an accelerator that accelerates a charged particle beam, and an irradiation device that includes a scanning electromagnet device that deflects the charged particle beam emitted from the accelerator to change the irradiation position on the irradiation target; A control device is provided that divides the irradiation position at a certain depth of the irradiation target into a plurality of sets, and controls the scanning electromagnet apparatus so as to irradiate a charged particle beam for each of the divided sets.

  According to the present invention, a dose distribution according to an irradiation plan can be formed, and the irradiation time (treatment time) can be shortened compared to conventional repaint irradiation.

It is a figure which shows the whole schematic structure of the charged particle beam irradiation system which is one Example of this invention. It is a block diagram which shows the structure of the irradiation control apparatus with which the charged particle beam irradiation system which is one Example of this invention is equipped. It is a figure which shows the dose distribution of the horizontal direction obtained when a charged particle beam is irradiated to irradiation object. It is a figure which shows dose distribution of the depth direction obtained when a charged particle beam is irradiated to irradiation object. It is a figure which shows the irradiation position and irradiation order which are one Example of this invention. It is drawing which shows the database structure showing the irradiation position which is one Example of this invention. It is the flowchart which showed the procedure in which the particle beam irradiation system which is one Example of this invention irradiates a particle beam. It is a figure which shows the example of the dose distribution at the time of target movement. It is a figure which shows the irradiation position and irradiation order which are one Example of this invention. It is a figure which shows the irradiation position and irradiation order which are one Example of this invention.

  Hereinafter, a preferred embodiment of a charged particle beam irradiation system in which irradiation positions are divided into sets and irradiation is performed for each set will be described. Charged particle beams include proton beams and carbon beams. In this embodiment, a proton beam will be described as an example. A charged particle beam irradiation system 100 according to the present embodiment includes a charged particle beam generator 1, a beam transport system 2, an irradiation chamber 17, and a control system 7. The configuration of the charged particle beam irradiation system 100 will be described with reference to FIG.

  The charged particle beam generator 1 includes an ion source that generates protons, a linac 3 that accelerates protons generated by the ion source, and an accelerator 4 that further accelerates proton beams accelerated by the linac. In this embodiment, a synchrotron will be described as an example of the accelerator 4, but a cyclotron may be used. The synchrotron 4 of the present embodiment has a high frequency application device and an acceleration device.

  The beam transport system 2 includes a beam path 12, a deflection electromagnet, and a quadrupole electromagnet. The beam path 12 is connected to the synchrotron 4 and an irradiation device 21 installed in the irradiation chamber 17.

  The irradiation chamber 17 includes a rotating gantry that can change the direction in which the irradiation target 51 is irradiated with the proton beam. The irradiation device 21 rotates with the rotating gantry. In the irradiation chamber 17, an irradiation device 21 and a couch (support device) 32 that supports the irradiation target 51 are provided. The irradiation target 51 is installed on a bed called a couch 32 that can freely move in three dimensions.

  The irradiation device 21 will be described with reference to FIG. The irradiation device 21 includes a scanning electromagnet device (Y-axis scanning electromagnet 23 and X-axis scanning electromagnet 24), a scatterer 25, a ridge filter 26, a flatness monitor 27, a dose monitor 28, a range shifter 29, and a collimator from the upstream side in the beam traveling direction. 30 and a bolus 31.

The scanning electromagnet device deflects the proton beam emitted from the synchrotron 4 to change the irradiation position on the patient (irradiation target) 52 as the irradiation target 51. The scanning electromagnet includes a Y-axis scanning electromagnet 23 and an X-axis scanning electromagnet 24. The Y-axis scanning electromagnet 23 and the X-axis scanning electromagnet 24 scan the passing proton beam in the horizontal direction (X-axis direction and Y-axis direction). Here, the lateral direction is a direction perpendicular to the beam axis. The scatterer 25 expands the beam diameter of the passing proton beam. The ridge filter 26 has a wedge shape, adjusts the energy distribution of the proton beam, and makes the dose distribution in the depth direction uniform. The flatness monitor 27 measures the flatness of the proton beam, and the dose monitor 28 measures the irradiation dose. The range shifter 29 is used for fine adjustment of proton beam energy. The collimator 30 has an opening through which the proton beam passes, and makes the dose distribution shape in the lateral direction of the proton beam coincide with the shape of the irradiation target.
The bolus 31 adjusts the arrival depth of the irradiation target 51 for each direction perpendicular to the traveling direction of the proton beam. By passing the proton beam through the bolus 31, the range of the proton beam can be adjusted for each position in the lateral direction in accordance with the shape of the affected part (irradiation target) 52 of the irradiation target 51.

  As shown in FIG. 1, the control system 7 includes a central controller 46, an accelerator controller 47, and an irradiation controller 48. The central controller 46 is connected to an accelerator controller 47 and an irradiation controller 48. The central controller 46 receives parameters necessary for irradiation from the database 42 and controls the accelerator controller 47 and the irradiation controller 48 based on these parameters to control proton irradiation. A database 42 is connected to the irradiation planning device 41 and the central control device 46. The database 42 records the data created by the irradiation planning device 41 and transmits it to the central control device 46 as necessary. The accelerator controller 47 is connected to the charged particle beam generator 1 and the beam transport system 2 and controls equipment provided in the charged particle beam generator 1 and the beam transport system 2. The irradiation control device 48 is connected to the irradiation device 21 and controls equipment provided in the irradiation device 21.

First, a method in which the charged particle beam irradiation system 100 of the present embodiment forms a uniform dose distribution in the lateral direction will be described. The irradiation apparatus 21 of the present embodiment scans a proton beam whose diameter is enlarged by the scatterer 25 with the Y-axis scanning electromagnet 23 and the X-axis scanning electromagnet 24 to form a distribution in the horizontal direction.
The X axis and the Y axis are directions perpendicular to the beam axis, and the X axis and the Y axis indicate directions orthogonal to each other.
Here, as a scanning method, there are a continuous scan for scanning without stopping the emission of the proton beam and a discrete scan for stopping the emission of the proton beam when changing the irradiation position. In this embodiment, discrete scanning will be described as an example, but it can also be applied to continuous scanning. In the case of discrete scanning, a Gaussian distribution of dose distribution irradiated on a certain place is called a spot. A uniform dose distribution can be formed in the lateral direction by arranging the spots at the same dose value at equal intervals. FIG. 3 shows the dose distribution in the X direction. As shown in FIG. 3, a uniform dose distribution is formed in the lateral direction by arranging spots with Gaussian distribution at equal intervals.

  Next, formation of a dose distribution in the beam traveling direction (depth direction from the body surface) of the proton beam will be described. In the depth direction, the Bragg peak is expanded by the ridge filter 26 to form a uniform dose distribution. The ridge filter 26 has a wedge shape, and the thickness varies depending on the position in the lateral direction. The proton beam loses different energy depending on its thickness. FIG. 4A shows the dose distribution in the depth direction when the ridge filter 26 is not used, and FIG. 4B shows the dose distribution using the ridge filter 26. Proton beams of different energies are mixed at an appropriate ratio by the ridge filter 26, and the proton beams form a uniform dose distribution in the depth direction. In this embodiment, an example in which the ridge filter 26 changes the energy of the proton beam will be described. However, the energy of the proton beam can be adjusted by the charged particle beam generator 1. In this case, a uniform dose distribution is formed in the depth direction by sequentially changing and irradiating the energy of the proton beam emitted from the charged particle beam generator 1 without using the ridge filter 26.

  As described above, the proton beam forms a uniform dose distribution in the lateral direction and the depth direction by adjusting the spread and energy of the proton beam in the lateral direction. Furthermore, a dose distribution that matches the shape of the target is formed using the range shifter 29, the bolus 31, and the collimator 30. The range shifter 29 absorbs the energy of the proton beam so that the dose distribution matches the target depth. The bolus 31 adjusts the arrival position of the dose distribution for each lateral position according to the shape of the target in the depth direction. The collimator 30 collimates the proton beam according to the shape of the target in the lateral direction.

  Next, a procedure for forming a proton beam dose distribution on the irradiation target 52 will be described. An operator such as a doctor uses the irradiation planning device 41 in advance to determine the energy of the proton beam, the size of the irradiation field, the total irradiation amount, the ridge filter 26, the range shifter 29, the collimator based on the image data captured by the X-ray CT apparatus 40. The shape of 30 and the shape of the bolus 31 are determined and registered in the database.

  Before starting the irradiation, the operator places the irradiation object 51 on the couch 32 and moves the couch 32 to the planned position. A collimator 30 and a bolus 31 created in advance are installed in the irradiation device 17. The central controller 46 reads the energy, the size of the irradiation field, the total irradiation amount, the ridge filter 26 and the range shifter 29 registered in the database 42.

  The central control device 46 sets the ridge filter 26 and the range shifter 29 in the irradiation device 17 to those designated by the irradiation planning device 41 via the irradiation control device 48 based on the information of the ridge filter 26 and the range shifter 29 read from the database. . Further, the central controller 46 determines the irradiation position and irradiation amount of each spot from the size of the irradiation field and the total irradiation amount.

  A method for determining the irradiation position and the irradiation amount will be described. The irradiation position is predetermined according to the size of the irradiation field. For example, as shown in FIG. 5A, the irradiation positions are arranged at equal intervals. Since the interval between irradiation positions is determined by the beam size (expansion of proton beam), more irradiation positions are set when a large irradiation field is formed. Here, the number of irradiation positions is ns. In the example of FIG. 5A, ns = 36. The irradiation dose d of the spot is calculated from the number of irradiation positions ns and the total irradiation dose D0 output from the irradiation planning device 41. Assuming that the amount of charge accumulated in the synchrotron 4 is Da, the number of accelerations / decelerations nr necessary for the synchrotron 4 can be expressed by nr = D0 / Da. If nr contains a decimal, carry it up. The dose irradiated in one cycle can be expressed as D0 / nr. Since ns irradiation positions are irradiated in one cycle of acceleration / deceleration of the synchrotron 4, the irradiation amount d irradiated to one spot is d = D0 / nr / ns.

  Here, for simplification of description, description will be made on the assumption that all irradiation positions have the same irradiation amount, but they need not be the same. The penumbra can be made steep by increasing the irradiation amount of the outermost spot.

  As described above, after determining the irradiation position and the irradiation amount, the irradiation positions of X and Y are determined in the irradiation order as shown in the table of FIG. The irradiation device 17 converts the values in this table into current values for exciting the X-axis scanning electromagnet 24 and the Y-axis scanning electromagnet 23 in consideration of the energy of the proton beam. The X-axis scanning electromagnet 24 and the Y-axis scanning electromagnet 23 are excited with the converted excitation current value to irradiate a desired irradiation position.

  The feature of this embodiment is in the order of spot irradiation, and the irradiation position (spot) at a certain depth (in the same layer) of the irradiation target 52 is divided into a plurality of sets, and a proton beam for each divided set. Is to irradiate. In particular, in this embodiment, a set is formed so that adjacent spots belong to different sets in the same layer, and a proton beam is irradiated for each set. In order to form a uniform dose distribution, a method of arranging irradiation positions at equal intervals is generally used, and conventionally, irradiation positions arranged at equal intervals have been sequentially irradiated from the end. In this embodiment, every other irradiation position is irradiated. FIG. 5A shows a conventional spot arrangement, and a circle indicates an irradiation position. A line connecting the circles represents a scanning path. Irradiation is started from the upper left position, adjacent spots are sequentially irradiated, and the lower left position is irradiated to complete irradiation of all irradiation positions. FIG. 5B shows the irradiation order of this embodiment. In the present embodiment, the irradiation control device 48 controls the irradiation order of the spots that irradiate the proton beam in each layer of the irradiation target 52 divided into a plurality in the traveling direction of the proton beam. The irradiation control device 48 changes the irradiation position of the proton beam in the direction parallel to the X axis (X axis direction) by changing the excitation current excited in the X axis scanning electromagnet 24, and the irradiation order in the X axis direction. To control. In addition, the irradiation control device 48 changes the excitation current excited in the Y-axis scanning electromagnet 23 to thereby irradiate the proton beam in a direction (Y-axis direction) parallel to the Y-axis that is perpendicular to the X-axis. To change the irradiation order in the Y-axis direction. The irradiation controller 48 irradiates the proton beam in an irradiation order such that irradiation positions adjacent in the X-axis direction belong to another set and irradiation positions adjacent in the Y-axis direction belong to another set. Specifically, as shown in FIG. 5B, among the irradiation positions arranged on the scanning path, the irradiation positions arranged adjacent to each other are alternately circled (first set) and triangular mark ( First, the set of irradiation positions indicated by circles is sequentially irradiated to reach the lower left. Thereafter, the irradiation position is returned to the upper left irradiation position, and a set of irradiation positions indicated by triangular marks is sequentially irradiated. When the irradiation position of the triangle mark on the lower left is irradiated, the irradiation in the corresponding layer is completed. When irradiation with a certain layer is completed, similarly with the next layer, proton beams are irradiated for each set in which adjacent irradiation positions belong to another set.

  A series of irradiation is started when the operator presses an irradiation start button on an operation console connected to the central controller 46. An irradiation procedure will be described with reference to FIG.

  In step S201, irradiation is started from cycle number i = 1 and irradiation position number j = 1.

  In step S202, the accelerator controller 47 controls the synchrotron 4 to accelerate the proton beam to the energy specified by the central controller 46. The proton beam enters the synchrotron 4 from the linac 3 and is accelerated by the acceleration device while circling the synchrotron 4. Further, the accelerator control device 47 controls the beam transport system 2 and excites the electromagnet so that the proton beam can reach the irradiation device 21.

  In step S203, the irradiation control device 48 excites the X-axis scanning electromagnet 24 and the Y-axis scanning electromagnet 23 to irradiate the first irradiation position shown in FIG.

  In step S204, when excitation of the scanning electromagnet device is completed, an emission signal is output from the irradiation control device 48 to the accelerator control device 47. The accelerator controller 46 controls the high frequency application device to apply a high frequency to the proton beam. The proton beam to which the high frequency is applied is scanned by the irradiation device 21 through the beam transport system 2 and reaches the first irradiation position. The irradiation amount that the proton beam has passed through the irradiation device 21 is measured by the dose monitor 28, and when the amount reaches the irradiation amount d, an emission stop signal is transmitted from the irradiation control device 48 to the accelerator control device 47. The accelerator controller 47 stops the high-frequency application device when receiving the emission stop signal, and stops the emission of the proton beam. After stopping the proton beam emission, the irradiation control device 48 returns to step S203 to irradiate the next irradiation position, and changes the excitation amount of the scanning electromagnet device. When j = ns is satisfied in step S205, the accelerator control device 47 controls the synchrotron 4 to decelerate and prepare for the next irradiation in step S206. When i = nr is reached in step S207, irradiation is completed in step S208.

  Here, the principle of improving the dose uniformity according to this embodiment will be described. The movement of the target causes a change in the spot position. In the conventional example, there is a possibility that spots whose positions change are concentrated in one place. On the other hand, in the present embodiment, spots whose positions vary are spatially dispersed. Therefore, a more uniform dose distribution can be formed. FIG. 8 (a) shows how the dose distribution changes due to the movement of the target when 10 spots are irradiated by the conventional irradiation method. The numbers indicate the order of irradiation, and irradiation is performed in order from the left. Assume that the target position has moved to the left when irradiating the second to fourth spots indicated by the dotted lines. When irradiation is performed when the target moves to the left, the right of the position where the target is intended to be irradiated is irradiated. A position where the dose value increases is generated by moving the second to fourth spots to the right. On the other hand, FIG. 8B shows a dose distribution when the present embodiment is applied. As in the case of FIG. 8A, the second to fourth spots indicated by dotted lines are moved to the right. In this embodiment, the irradiation order of the spots is different from the conventional order as shown by numerals. That is, after irradiating one spot, a spot at two positions away is irradiated. At this time, a spot irradiated to an unplanned position represented by a dotted line appears at a position that is not adjacent. In this way, by dispersing the spots irradiated to unplanned positions, it is possible to reduce changes in dose values caused by changes in target positions. In fact, comparing the maximum dose values in FIG. 8 (a) and FIG. 8 (b), FIG. 8 (b) is smaller.

  In this embodiment, as an example in which the irradiation position at a certain depth (in the same layer) of the irradiation target 52 is divided into a plurality of sets and a proton beam is irradiated for each divided set, FIG. As shown, an example is shown in which irradiation is performed every other irradiation position arranged adjacently on the scanning path. Instead of FIG. 5 (b), the irradiation order may be such that irradiation is performed every other two as shown in FIG. In this case, the irradiation control device 48 divides the irradiation positions arranged on the scanning path into three sets so that the irradiation positions arranged adjacent to each other in the X-axis direction belong to different sets. Irradiate a proton beam to each set. Specifically, in the example of FIG. 9, among the irradiation positions arranged on the scanning path, the irradiation position of the circle (first set) is irradiated first, and then the triangle mark (second set). , And finally the irradiation position of the square mark (third set) is irradiated. In addition, it is not limited to the example divided | segmented into three sets, You may divide | segment into several sets.

  Moreover, it is good also as an irradiation order which irradiates by a column unit, such as every other row. In this case, the irradiation positions adjacent in the X-axis direction are set as the same set, and the irradiation positions adjacent in the Y-axis direction are set as another set. In the irradiation control device 48, among irradiation positions at a certain depth (in the same layer) of the irradiation target, irradiation positions adjacent in the X-axis direction belong to the same set, and irradiation positions adjacent in the Y-axis direction are different. A proton beam is irradiated for each set that belongs to the set. Specifically, as shown in FIG. 10, when the scanning path along the X-axis direction is the first column, the second column,..., The Nth column, the odd numbered columns (the first column, the third column) of the scanning path. After irradiating the irradiation position of the circle mark (first set) arranged on the eyes,..., It is arranged on the even-numbered rows (second row, fourth row,...) Of the scanning path. The irradiation position of the triangle mark (second set) is irradiated. A dotted line in FIG. 10 indicates a scanning path when the irradiation position of the triangle mark is irradiated.

  In this embodiment, it is assumed that all irradiation positions are irradiated once for each cycle of the synchrotron 4. However, in order to increase the number of repaints in order to form a more uniform dose distribution, the synchrotron 4 All irradiation positions may be repeatedly irradiated twice or more within a cycle.

  In this embodiment, a cyclotron may be used instead of the synchrotron 4 of the charged particle beam generator 1. In the case of using a cyclotron, this embodiment can be implemented by designating nr by the operator.

  Note that gate irradiation may be combined to form a uniform dose distribution on the moving irradiation target 52. Gate irradiation is a method of emitting a proton beam only when the irradiation target 52 is within a predetermined emission permission range. When performing gate irradiation, the proton beam emission stops at the moment when the irradiation target 52 leaves the emission permission range. Moreover, after the irradiation target 52 comes out of the emission permission range, irradiation may be completed at all irradiation positions and emission may be stopped. In addition, after the irradiation target 52 has exited the emission permission range, the emission may be stopped after the irradiation of the set of irradiation positions described with reference to FIG. By completing irradiation of all irradiation positions or a set of irradiation positions, it is possible to suppress a change in the interval between irradiation positions and form a more uniform dose distribution. Further, when the irradiation of the set of irradiation positions is completed, the time from when the irradiation target 52 exits the emission permission range to when the irradiation of the proton beam stops is more uniform than when the irradiation of all irradiation positions is completed. A simple dose distribution can be formed.

  In addition, a present Example can be applied to the irradiation method which measures an irradiation amount for every irradiation position, moves to the next irradiation position after reaching a setting value. In particular, the present invention can also be applied when the emission of proton beams is not stopped.

  The present embodiment is not limited to the method of matching the uniform dose distribution with the shape of the irradiation target 52 using the bolus 31 and the collimator 30, and the target is adjusted by scanning the proton beam and adjusting the irradiation amount for each irradiation position. It can also be applied to an irradiation method for forming a dose distribution that matches the shape of the above.

  The irradiation order which is a feature of the present embodiment may be determined by the charged particle beam irradiation system 100 or the irradiation planning device 41. The irradiation planning device 41 creates irradiation plan information used for the charged particle beam irradiation system 100. When the irradiation planning device 41 determines the irradiation order of spots, the irradiation planning device 41 is at a certain depth (in the same layer) of the irradiation target. Irradiation plan information is created so that the irradiation position is divided into a plurality of sets and a proton beam is irradiated for each of the divided sets. In the case of the irradiation order shown in FIG. 5B, the irradiation order is such that irradiation positions adjacent in the X-axis direction belong to another set, and irradiation positions adjacent in the Y-axis direction belong to another set. The irradiation plan apparatus 41 creates irradiation plan information. In the case of the irradiation sequence shown in FIG. 9, among the irradiation positions at a certain depth (in the same layer) of the irradiation target, three irradiation positions arranged adjacent to each other in the X-axis direction belong to different sets. The irradiation plan apparatus 41 creates irradiation plan information so that it is divided into sets and the irradiation order is such that a proton beam is irradiated for each of the divided sets. In the case of the irradiation sequence shown in FIG. 10, among irradiation positions at a certain depth (in the same layer), irradiation positions adjacent to each other in the X-axis direction belong to the same set, and irradiation positions adjacent to each other in the Y-axis direction. The irradiation planning device 41 creates irradiation plan information so that the irradiation order of irradiating proton beams for each set such that belongs to another set.

  According to the present embodiment, the scanning distance required to irradiate all the spots becomes twice or more. On the other hand, since the number of spots does not change, there is no change in the time for emitting the proton beam. If the time for scanning and the time for emitting the proton beam are compared, the scanning time can be sufficiently shortened, so the influence of the scanning time on the entire irradiation time is negligible. Therefore, according to the present invention, a more uniform dose distribution can be formed with substantially the same irradiation time. In addition, a uniform dose distribution equivalent to the conventional one can be formed with a shorter irradiation time.

DESCRIPTION OF SYMBOLS 1 Charged particle beam generator 2 Beam transport system 3 Linac 4 Synchrotron 7 Control system 12 Beam path 17 Irradiation chamber 21 Irradiator 23 Scanning magnet 24 Scanning magnet 25 Scattering body 26 Ridge filter 27 Flatness monitor 28 Dose monitor 29 Range shifter 30 Collimator 31 Bolus 32 Couch 40 X-ray CT
41 Irradiation Planning Device 42 Database 46 Central Controller 47 Accelerator Controller 48 Irradiation Controller 51 Irradiation Object 52 Irradiation Target 100 Charged Particle Beam Irradiation System

Claims (3)

An accelerator to accelerate the charged particle beam;
A scanning electromagnet device that deflects the charged particle beam emitted from the accelerator to change the irradiation position on the irradiation target, a scatterer that expands the beam diameter of the charged particle beam, and a traveling direction of the charged particle beam An irradiation apparatus comprising: a bolus that adjusts an arrival depth of the charged particle beam in each vertical direction; and a collimator having an opening through which the charged particle beam passes;
A controller for controlling the scanning electromagnet device so as to divide the irradiation position at a certain depth of the irradiation target into a plurality of sets and irradiate the charged particle beam for each of the divided sets;
The plurality of sets are determined so that the irradiation positions that are adjacent to each other on the scanning path on which the charged particle beam is irradiated by the scanning electromagnet apparatus belong to different sets.
The irradiation position included in at least one of the plurality of sets has an arrangement position in a direction corresponding to a long line segment among line segments in two orthogonal directions constituting the scanning path which is a main scanning direction. The charged particle beam irradiation system, wherein the charged particle beam irradiation systems are arranged at different positions on the long line segments adjacent to each other in the direction corresponding to the short line segment among the two line segments orthogonal to each other. The scanning electromagnet device comprises:
A first scanning electromagnet that scans the charged particle beam in a first direction ;
A second scanning electromagnet that scans the charged particle beam in a second direction orthogonal to the first direction;
The controller is
The scanning is performed so that the charged particle beam is irradiated for each of the irradiation positions adjacent to each other in a direction parallel to the first direction among the irradiation positions at a certain depth of the irradiation target. 2. The charged particle beam irradiation system according to claim 1, wherein the electromagnet device is controlled. The controller is
The charged particle beam irradiation system according to claim 1, wherein the energy of the charged particle beam emitted from the accelerator is changed.