WO2018211576A1

WO2018211576A1 - Particle beam irradiation apparatus

Info

Publication number: WO2018211576A1
Application number: PCT/JP2017/018281
Authority: WO
Inventors: 裕介坂本; 泰三本田
Original assignee: 株式会社日立製作所
Priority date: 2017-05-16
Filing date: 2017-05-16
Publication date: 2018-11-22
Also published as: TWI659763B; TW201900235A

Abstract

The purpose of the present invention is to perform scanning irradiation in such a way as to deliver a sufficient dose throughout the interior of a tumor while keeping the dose delivered outside the tumor as low as possible. This particle beam irradiation apparatus (50) is provided with: a particle beam generation/delivery device (1) for delivering and blocking an accelerated particle beam (10) and changing the energy thereof; a scanning device (2) for deflecting the particle beam (10) in two directions which are perpendicular to the direction of the propagation thereof, and thereby moving an irradiation spot (12); a collimator (6) which has an opening (74) extending in a direction perpendicular to a reference irradiation axis (60) and blocks the passage of the particle beam (10) outside of the opening (74), the opening (74) having a changeable shape; a collimator information storage unit (32) for storing information (data1) relating to the opening shape of the collimator (6); and a control device (4) for controlling the particle beam generation/delivery device (1), the scanning device (2) and the collimator (6). When the particle beam (10) is emitted at an object (11) to be irradiated, the control device (4) outputs, to the collimator (6), a collimator control signal (sig1) for setting the opening shape of the collimator (6) on the basis of the information (data1) relating to the opening shape of the collimator (6).

Description

Particle beam irradiation equipment

The present invention relates to a particle beam treatment apparatus for performing treatment by irradiating an affected area such as a tumor with a particle beam, and relates to a particle beam irradiation apparatus used for irradiating a predetermined dose according to the three-dimensional shape of the affected area. .

Particle beam therapy uses a device such as an accelerator to accelerate charged particles such as protons or carbon ions to several hundred mega-electron volts, and irradiates the patient to give a dose to the tumor in the body to treat cancer. It is a method to do. At this time, it is important to form a dose distribution instructed by the doctor, that is, a dose distribution as close as possible to the target distribution for the tumor. In many cases, the target distribution is such that the dose is uniform within the tumor and is as low as possible outside the tumor than inside the tumor.

Generally, when an object (including a human body) is irradiated with a particle beam accelerated by an accelerator, the three-dimensional dose distribution in the object has a characteristic that the dose has a maximum peak. This maximum dose peak is called the Bragg peak. In addition, when there is a maximum dose peak at one point in the three-dimensional space, the peak position is defined as the “irradiation position” of the particle beam. In order to form the target distribution three-dimensionally using the particle beam having the peak structure as described above, some device is required.

There are multiple ways to form a target distribution. One of the methods for forming the target distribution is a layered product irradiation method. In Patent Document 1, a scanning electromagnet for horizontal scanning and vertical scanning for scanning a charged particle beam (particle beam) in the horizontal direction, and the irradiation field of the charged particle beam are substantially the same as the shape of each divided layer of the affected area. Particles equipped with a multi-leaf collimator that squeezes to become a bolus that is a patient-specific tool for matching the dose distribution in the depth direction to the bottom shape of the affected area, and a range shifter for finely adjusting the arrival depth of the charged particle beam A line therapy device is disclosed. Since the particle beam therapy apparatus of Patent Document 1 uses a bolus, the deepest layer irradiates the maximum outer periphery of the affected area as seen from the beam traveling direction, so the multi-leaf collimator opening of the deepest layer is maximized and shallow. The charged particle beam is irradiated while the aperture of the multi-leaf collimator is made smaller as the layers are formed. Patent Document 1 discloses that raster scanning, zigzag scanning, single-circle scanning, helical scanning, and line scanning can be used as scanning of charged particle beams in each layer. An example of performing a layered body irradiation method using a particle beam therapy system equipped with a multi-leaf collimator and a bolus is also disclosed in Patent Document 2 and Patent Document 3.

Also, as another method for forming the target distribution, there is a scanning irradiation method. In order to use this method, first, using an electromagnet or the like, a mechanism for arbitrarily deflecting the particle beam in two directions perpendicular to the Z direction as the particle beam traveling direction, that is, in the X and Y directions, is used. . Furthermore, the function which adjusts arbitrarily the position where a Bragg peak is formed in a Z direction by adjustment of particle energy is required. Generally, a particle beam generating and transporting apparatus that transports and blocks particle beams includes an accelerator that accelerates the particle beam, and this accelerator also has an energy adjustment function. A plurality of irradiation positions (also referred to as spots) are set in the tumor, and particle beams are sequentially irradiated to the respective spots using the above two mechanisms. The balance of doses to be given to each spot is adjusted and determined in advance, and the respective dose distributions given to each spot are added together, thereby forming a target distribution as a result.

Generally, it takes 1 ms or less to move the irradiation direction of the particle beam in the XY direction and move from one spot to the next spot, and it takes time to move the Bragg peak position in the Z direction by changing the energy. The time is about 100 ms. For this reason, the order of irradiating each irradiation position is to scan the particle beam in the XY direction with one energy, irradiate all the spots corresponding to the energy, and then switch to the next energy. Is common. At this time, a set of all spots corresponding to one energy is called a slice. When changing the slice (ie changing the energy), the irradiation of the particle beam must be stopped.

The balance of the dose given to each spot is determined by the treatment planning device. At this time, the sum of the dose distributions to be given to all spots included in one slice (referred to as slice dose distribution) does not necessarily have to be a uniform distribution within the tumor. The sum of all slice dose distributions only needs to be uniform within the tumor, and there is no particular restriction on the single slice dose distribution. There is a possibility that a small distribution can be formed.

In general, in the scanning irradiation method, spots can be arbitrarily arranged in three dimensions according to the shape of the tumor to be irradiated. Therefore, unlike the particle beam therapy apparatus of Patent Documents 1 to 3, XY two-dimensional Equipment such as a collimator that blocks unwanted doses outside the tumor in the direction is not necessary. In addition, if there are healthy organs around the tumor that do not want to receive a dose as much as possible (called risk organs), do not place a spot near the risk organ, or if a spot is placed, Measures may be taken, such as adjusting the dose to a lesser extent.

Japanese Patent No. 5637055 (FIGS. 2 to 4) JP 2010-187900 A (FIG. 2) Japanese Patent No. 5059723 (FIG. 1)

In the scanning irradiation method, the size of the dose distribution given to one spot in the XY direction (referred to as spot size) is approximately 5 mm to 10 mm, although it varies depending on the conditions. Therefore, if a sufficient dose is to be applied to the entire inside of the tumor, it is inevitable that the dose is applied to a portion close to the tumor in a healthy organ outside the tumor. In particular, when the distance between the tumor and the risk organ is about the same as or smaller than the spot size, that is, there is a trade-off relationship between giving a dose to the tumor and avoiding the dose to the risk organ, and at least one of them One goal may need to be relaxed.

The present invention solves the above-mentioned problems, and provides a particle beam irradiation apparatus that performs scanning irradiation so as to minimize the dose application to the outside of the tumor while giving a sufficient dose to the entire inside of the tumor. One purpose. It is also a second object of the present invention to provide a particle beam irradiation apparatus that performs scanning irradiation that achieves both dose application to the tumor and avoidance of dose application to the risk organ even when the distance between the tumor and the risk organ is short. The purpose.

The particle beam irradiation apparatus of the present invention is a particle beam irradiation apparatus that irradiates a particle beam for each cross section of an irradiation target perpendicular to the reference irradiation axis of the particle beam. The particle beam irradiation apparatus of the present invention has an energy changing mechanism that changes the energy of the particle beam, and is transported from the particle beam generating and transporting apparatus that transports and blocks the accelerated particle beam and the particle beam generating and transporting apparatus. A scanning device that deflects the particle beam in two directions perpendicular to the traveling direction and moves the irradiation position to irradiate the irradiation target, and an opening shape that has an opening in the direction perpendicular to the reference irradiation axis and is the shape of the opening Can control the collimator that blocks the passage of the particle beam outside the aperture, the collimator information storage unit that stores information about the aperture shape of the collimator, and the particle beam generation and transport device, the scanning device, and the collimator including the energy change mechanism A collimator for setting the collimator aperture shape based on information on the collimator aperture shape when the control device irradiates the irradiation target with the particle beam. And outputs the motor control signal to the collimator.

The particle beam irradiation apparatus of the present invention includes a collimator whose opening shape can be changed, and the opening shape of the collimator is set based on information on the opening shape of the collimator, so that a sufficient dose is given to the entire inside of the tumor. Scanning irradiation can be performed so as to minimize the external dose application.

It is a schematic block diagram of the particle beam irradiation apparatus by Embodiment 1 of this invention. It is a figure which shows an example of the collimator of FIG. It is a flowchart which shows operation | movement of the particle beam irradiation apparatus of FIG. It is a schematic diagram explaining the positional relationship of the collimator of FIG. 1 and irradiation object. It is a schematic diagram explaining the positional relationship of the collimator of FIG. 1 and irradiation object. It is a figure explaining the distribution of the X direction of the dose provided to the slice of the irradiation object of FIG. FIG. 5 is a diagram for explaining a collimator opening projected onto the irradiation target slice of FIG. 4 and a cut surface at the center line of the irradiation target slice; FIG. 5 is a diagram for explaining a collimator opening projected onto the irradiation target slice in FIG. 4 and a cut surface at the center line in the irradiation target slice when the risk organ is in the vicinity. It is another flowchart which shows operation | movement of the particle beam irradiation apparatus of FIG. It is a schematic block diagram of the other particle beam irradiation apparatus by Embodiment 1 of this invention. It is a schematic block diagram of the other particle beam irradiation apparatus by Embodiment 1 of this invention. It is a schematic block diagram of the other particle beam irradiation apparatus by Embodiment 1 of this invention. It is a figure which shows the hardware constitutions which implement | achieve the functional block of the opening shape calculating part of FIG.1, FIG.10, FIG.11 and FIG. FIG. 10 is a diagram for explaining a setting example of a collimator opening shape in the collimator of the second embodiment. It is a figure explaining the distribution to the Z direction of the irradiation dose with respect to the spot of FIG. It is a figure explaining the distribution to the X direction of the irradiation dose with respect to the spot of FIG. It is a figure explaining the distribution to the Y direction of the irradiation dose with respect to the spot of FIG. It is a figure explaining the subject in the positional relationship of a collimator opening shape, irradiation object, and a slice. It is a figure explaining the subject in the positional relationship of a collimator opening shape, irradiation object, and a slice. It is a figure explaining the overlap of the dose distribution of the X direction by the slice of FIG. 18, FIG. It is a figure explaining the specific example of the setting method of the collimator opening shape in the collimator of Embodiment 2. FIG. It is a figure explaining the specific example of the setting method of the collimator opening shape in the collimator of Embodiment 2. FIG. It is a figure explaining the collimator opening projected on the slice of irradiation object of FIG. 21, and the projection irradiation object outer periphery projected on the said slice. It is a figure explaining the overlap of the dose distribution of the X direction by the some slice in the collimator of Embodiment 2. FIG. It is a figure explaining the distribution of the X direction of the dose provided to the slice of irradiation object in case the energy of particle beam is high. It is a figure which shows the relationship between the energy of particle beam, and the lateral spread length of a dose.

Embodiment 1 FIG.
FIG. 1 is a schematic configuration diagram of a particle beam irradiation apparatus according to Embodiment 1 of the present invention, and FIG. 2 is a diagram illustrating an example of a collimator in FIG. FIG. 3 is a flowchart showing the operation of the particle beam irradiation apparatus of FIG. 4 and 5 are schematic diagrams for explaining the positional relationship between the collimator in FIG. 1 and the irradiation target. FIG. 6 is a diagram for explaining the distribution in the X direction of the dose given to the irradiation target slice of FIG. FIG. 7 is a diagram for explaining the collimator opening projected onto the irradiation target slice of FIG. 4 and the cut surface at the center line of the irradiation target slice. FIG. 8 is a diagram for explaining a collimator opening projected onto the irradiation target slice of FIG. 4 and a cut surface at the center line of the irradiation target slice when the risk organ is in the vicinity.

The particle beam irradiation apparatus 50 according to the first embodiment of the present invention accelerates charged particles to a required energy, generates the accelerated charged particles as the particle beam 10 and transports them to the scanning device 2. 1 and the particle beam 10 generated by the particle beam generating / transporting device 1 are deflected in two directions perpendicular to the Z direction, that is, the traveling direction of the particle beam, that is, in the X and Y directions, and is irradiated in the patient tumor, that is, irradiation A scanning device 2 that scans an arbitrary position of the object 11 is provided. Usually, the particle beam generating and transporting apparatus 1 includes an accelerator for accelerating charged particles and a transport system for transporting the particle beam 10 from the accelerator to the scanning device 2. The scanning device 2 includes an X-direction scanning device 21 that deflects the particle beam 10 in the X direction and a Y-direction scanning device 22 that deflects the particle beam 10 in the Y direction.

Furthermore, the particle beam irradiation apparatus 50 includes a spot information storage unit 31 that stores position information of each spot 12 in the irradiation object 11, a dose value of the particle beam 10 to be irradiated to each spot 12, and the particle beam generation and transportation apparatus 1. The control device 4 that controls the start and interruption of the emission of the particle beam 10 by the scanning and the scanning of the particle beam 10 by the scanning device 2, and the particle beam 10 scanned by the scanning device 2 is irradiated to each spot 12 of the irradiation object 11. A dose monitor 5 that measures the dose value to be measured, a collimator 6 that has an opening 74 that extends in the XY direction, blocks the passage of the particle beam 10 outside the opening 74, and can arbitrarily set the opening shape, and a collimator And a collimator information storage unit 32 for storing information on the six aperture shapes. As the position information of each spot 12 stored in the spot information storage unit 31, for example, the spot number (irradiation position number), the position information of each spot 12 in the XY coordinate system, and the particle beam 10 are the X position and Y of each spot 12. There are an excitation current value of the scanning electromagnet of the scanning device 2 for deflecting to the position, energy corresponding to the Z position of each spot 12, and the like. The control device 4 controls the particle beam generating and transporting device 1 including the energy changing mechanism 9, the scanning device 2, and the collimator 6. The control device 4 controls the collimator 6 so as to control the shape of the opening 74 of the collimator 6.

The collimator 6 is, for example, a multi-leaf collimator. As shown in FIG. 2, the collimator 6 includes a plurality of leaves 7. In the collimator 6, a leaf pair composed of two leaves 7 is arranged in the longitudinal direction (X direction), and a plurality of leaf pairs of the leaf 7 are arranged in the respective thickness directions (Y direction). 7 is set, the opening 74 is formed. The collimator 6 forms the shape of the opening 74 based on the collimator control signal sig 1 output from the control device 4. The spot information storage unit 31 and the collimator information storage unit 32 are collectively referred to as a storage unit 3. The spot information storage unit 31 and the collimator information storage unit 32 may be the same as hardware or may be separate.

The collimator information storage unit 32 stores information on the shape of the openings 74 of at least two collimators 6, that is, information on the shape of the collimator openings. Information about the collimator aperture shape is associated with the energy of the corresponding particle beam 10. The collimator opening shape is a shape that is enlarged by adding a predetermined margin to the slice cross-sectional shape of the irradiation object 11. A method of determining the collimator opening shape will be described later.

1 shows an example in which the treatment planning device 51 determines the collimator opening shape and transmits collimator opening shape data data1 indicating the collimator opening shape to the collimator information storage unit 32. The treatment planning device 51 includes an opening shape calculation unit 52 that determines a collimator opening shape and generates collimator opening shape data data1.

The particle beam generating and transporting apparatus 1 includes an energy changing mechanism 9 that changes the energy of the particle beam 10. In general, when the type of accelerator that generates the particle beam 10 is a synchrotron, the energy of the particle beam can be changed by changing the operation pattern of the synchrotron. When the accelerator type is a cyclotron, the energy of the particle beam 10 can be changed by arranging an energy selection system (ESS) in the middle of the particle beam transport path. Moreover, as shown in FIG. 12, the range shifter 14 which changes the energy of the particle beam 10 may be incorporated in the particle beam irradiation apparatus 50. FIG. 12 is a schematic configuration diagram of another particle beam irradiation apparatus according to Embodiment 1 of the present invention. The range shifter 14 can be used regardless of whether the type of accelerator is a synchrotron or a cyclotron, and the energy can be changed using only the range shifter 14, or the operation pattern of the synchrotron can be changed. It may be used in combination or in combination with an energy selection system. The present invention can be applied regardless of the type of the energy changing mechanism 9 and the presence or absence of the range shifter 14.

The operation of scanning irradiation by the particle beam irradiation apparatus 50 of the first embodiment will be described with reference to FIG. In step F01, the irradiation operation to the irradiation object 11 is started. First, in step F02, the parameters of the particle beam generating and transporting apparatus 1 are set so that the energy of the particle beam 10 becomes energy corresponding to the first slice to be irradiated (energy setting procedure). In step F03, the opening shape of the collimator 6 is set to be the opening shape corresponding to the first slice (collimator opening setting procedure). Thereafter, in step F04, the particle beam 10 is generated to start irradiation (particle beam irradiation start procedure), and in step F05, slice irradiation which is particle beam irradiation for the set slice is executed (slice irradiation procedure). ).

The slice irradiation in the slice irradiation procedure is a repetition of the spot irradiation procedure (step F06) for irradiating each spot 12 in the slice and the spot scanning procedure (step F07) for scanning (moving) the position to be irradiated to the next spot 12. If irradiation to all the spots 12 in the slice is completed, the process proceeds to step F08. In step F08, the generation of the particle beam 10 by the particle beam generator / transporter 1 is interrupted to stop the particle beam irradiation (particle beam irradiation stop procedure). In step F09, it is determined whether or not the current slice is the last slice. If it is determined that the current slice is the last slice, the process ends (step F10). If it is determined in step F09 that the current slice is not the last slice, the process returns to step F02. In step F02, the energy of the particle beam 10 is set to be energy corresponding to the next slice to be irradiated. Thereafter, the opening shape of the collimator 6 is set to be the opening shape corresponding to the next slice (step F03), and particle beam irradiation to the next slice is started (step F04). The operations from step F02 to step F09 are repeated until the slice irradiation for all slices is completed, and when completed, the process ends (step F10).

Here, the opening shape corresponding to each slice may be different for each slice, or the same shape may exist. If the corresponding aperture shape in a certain slice does not change from the previous slice, the collimator aperture setting procedure (step F03) is omitted, that is, the process proceeds to step F04 without changing the collimator aperture setting.

The positional relationship between the collimator 6 and the irradiation object 11 in the irradiation of the particle beam 10 will be described with reference to FIGS. When scanning the particle beam 10 using the scanning device 2 such as an electromagnet, the scanning starting point P0 of the particle beam 10 can be defined, and the path (beam path 62) of the particle beam 10 toward each spot 12 is the scanning starting point. It can be drawn so as to spread radially around P0. When the particle beam 10 is not scanned by the scanning device 2, the particle beam 10 advances along the reference irradiation axis 60. The reference irradiation axis 60 is a reference axis that passes through an isocenter that is an irradiation reference of the particle beam irradiation apparatus 50. The collimator 6 is used for the purpose of suppressing unnecessary dose application to the outside of the irradiation target 11, but when the opening shape of the opening 74 of the collimator 6 is set, the opening of the collimator 6 projected from the scanning origin P0 to the slice. Attention should be paid to the positional relationship between the position of the end portion 74, that is, the position of the projection opening end portion, and the cross section of the slice of the irradiation object 11. The opening 74 of the collimator 6 extends in a direction perpendicular to the reference irradiation axis 60, and the opening shape of the opening 74 can be changed in a direction perpendicular to the reference irradiation axis 60.

In FIG. 4, the opening end line 63 is described at the position of the end of the opening 74 of the collimator 6, and the projected opening end line 64 is described at the position of the projecting opening end projected onto the slice. Since the slice is a set of all the spots 12 corresponding to one energy as described above, the position of the slice in the Z direction is indicated by the slice center line 61 in FIG. Note that the slice is appropriately expressed as a slice 61 by using a symbol of the slice center line 61. The slice center line 61 is perpendicular to the reference irradiation axis 60, and the slice is also perpendicular to the reference irradiation axis 60. FIG. 4 also shows a risk organ (risk target) 13. The symbol for the slice center line is generally 61, and 61a, 61b, 61c, 61d, 61e, and 61f are used in the case of distinction. The reference numeral of the opening end line is generally 63, and 63a and 63b are used in the case of distinguishing the description.

FIG. 5 shows the positions of the opening of the collimator 6 and the end of the projection opening with respect to slices having different positions in the Z direction. The slice center line 61a is the center line of the set of spots 12 on the deep side (the positive side of the Z axis, the downstream side of the particle beam path), and the slice center line 61b is the shallow side (the negative direction of the Z axis). Side, upstream of the particle beam path). In FIG. 5, the leaf 7b of the collimator 6 corresponding to the shallow slice 61b is indicated by a solid line, and the leaf 7a of the collimator 6 corresponding to the deep slice 61a is indicated by a broken line. FIG. 5 also shows the opening 74a and opening end line 63a of the collimator 6 corresponding to the slice 61a, and the opening 74b and opening end line 63b of the collimator 6 corresponding to the slice 61b. FIG. 5 shows an example in which the sizes of the

openings

74 a and 74 b of the collimator 6 corresponding to the two

slices

61 a and 61 b are different, that is, an example of the two collimator opening shapes of the collimator 6. Specifically, FIG. 5 shows an example in which the opening 74b of the collimator 6 corresponding to the shallow slice 61b is narrower than the opening 74a of the collimator 6 corresponding to the deep slice 61a. The leaf code is 7 as a whole, and 7a and 7b are used in the case of distinction. 74 is generally used as the symbol of the opening, and 74a and 74b are used in the case of distinction.

FIG. 6 is an example of the distribution in the X direction of the dose given to the slice. In FIG. 6, the vertical axis represents the dose, and the horizontal axis represents the position in the X direction. The dose distribution 65 is a dose distribution when the collimator 6 is provided, and the dose distribution 66 is a dose distribution when the collimator 6 is not provided. The broken line 67 indicates the tumor, that is, the end of the irradiation target 11, and the position of the broken line 67 in the X direction is the irradiation target end position Xt. The position in the X direction of the projected opening end line 64 indicating the position of the projected opening end projected onto the slice is the projected opening end position Xep. The difference between the irradiation target end position Xt and the projection opening end position Xep is an opening margin tm in the X direction.

In the treatment plan, spot placement and irradiation dose for each spot are determined so that a sufficient dose is given to the tumor (11 to be irradiated) and the dose is not given to the outside of the tumor as much as possible. A dose gradient in which the dose decreases from the portion toward the outside (from the broken line 67 to the positive side in the X direction) is formed. Compared to the conventional scanning irradiation that does not use the collimator 6 shown in the dose distribution 66, the scanning irradiation using the collimator 6 shown in the dose distribution 65 can realize a steeper dose gradient. Therefore, even if the irradiation dose to the tumor is the same, use of the collimator 6 can reduce unnecessary dose application outside the tumor (outside the irradiation target).

The method for determining the collimator aperture shape will be described. In order to give a sufficient dose to the entire tumor (the entire irradiation object 11), the collimator opening is set so that the end of the collimator opening projected onto the slice (projection opening end line 64) is outside the tumor. Must be set. A setting example of the collimator opening will be described with reference to FIG. FIG. 7 shows a cut surface of one slice in the tumor (irradiation target 11) and the opening 74 of the collimator 6 projected onto the slice. The irradiation target outer periphery 69 is the outer periphery of the cut surface in the slice of the tumor (irradiation target 11), and the projection opening end portion 68 is the end portion of the opening 74 of the collimator 6 projected onto the slice. In the particle beam irradiation apparatus 50 according to the first embodiment, an enlarged shape obtained by adding the opening margin tm of the collimator 6 to the irradiation target outer periphery 69 that is the outer periphery of the cut surface of the tumor slice is projected onto the slice. The shape of the collimator opening is set so as to coincide with the projection opening end 68 which is the end of the opening 74 of the collimator 6. By doing in this way, the particle beam irradiation apparatus 50 of Embodiment 1 can provide a sufficient dose to the entire inside of the tumor while suppressing unnecessary dose application outside the tumor.

In the example of FIG. 7, the opening margin tm of the collimator 6 is isotropic. That is, the size of the opening margin tm of the collimator 6 shown in two places in the figure is equal. However, when the risk organ (risk target) 13 is in the vicinity of the tumor (irradiation target 11), it may be desirable to change the opening margin tm of the collimator 6 as shown in FIG. In FIG. 8, since the risk organ outer periphery 70 that is the outer periphery of the risk organ 13 is near the irradiation target outer periphery 69 of the tumor (irradiation target 11), the opening margin of the collimator 6 in the region close to the risk organ outer periphery 70 is tm2. In the example, the opening margin of the collimator 6 in the region where the risk organ outer periphery 70 is not nearby is tm1. The opening margin tm2 is smaller than the opening margin tm1.

A region obtained by removing the irradiation target outer periphery 69 from the projection opening end portion 68 is an opening margin region. The opening margin region includes three types of regions, that is, a margin region Am1, a margin region Am2, and a margin transition region Am3. The margin area Am1 is an area having an opening margin of tm1, and is an area from the broken line 71a to the broken line 71d counterclockwise. The margin area Am2 is an area having an opening margin of tm2, and is an area from the broken line 71b to the broken line 71c in the clockwise direction. The margin transition area Am3 is an area where the opening margin is between tm1 and tm2, and is an area from the broken line 71a to the broken line 71b and an area from the broken line 71c to the broken line 71d.

The particle beam irradiation apparatus 50 according to the first embodiment sets the opening margin tm2 of the collimator 6 in the region close to the risk organ outer periphery 70 to be smaller than the opening margin tm1 in the region not close to the risk organ outer periphery 70. It is also possible to set a collimator aperture shape that blocks the irradiation of the particle beam 13. In this case, the irradiation dose is reduced inside the tumor in the vicinity of the risk organ 13 as compared with the case where the margin is set isotropically. However, in order to avoid giving the dose to the risk organ 13, stop. There are cases where you cannot get. In this case, if the particle beam irradiation apparatus 50 according to the first embodiment is used, a medical worker such as a doctor considers the balance between the disadvantage of reducing the irradiation dose to the tumor and the disadvantage of giving the dose to the risk organ 13. Then, an optimal solution (optimal treatment plan) can be determined using the treatment planning device 51. When the particle beam irradiation apparatus 50 according to the first embodiment cannot help giving a dose to the risk organ 13, the opening margin tm2 of the collimator 6 in the region near the risk organ outer periphery 70 of the risk organ 13 is unavoidable. Is set to be smaller than the opening margin tm1 in the region not close to the risk organ outer periphery 70, it is possible to avoid giving a dose to the risk organ 13.

The setting method of the opening margin tm2 of the collimator 6 in the region near the risk organ outer periphery 70 of the risk organ 13 is performed as follows. For example, first, an enlarged shape is created by adding the same predetermined margin (opening margin tm1) to the slice cross-sectional shape of the irradiation object 11. Next, the enlarged shape with the opening margin tm1 added is reduced based on the position of the risk organ 13 in the same cross section, and the irradiation dose in the tumor in the vicinity of the risk organ 13 and the exposure dose to the risk organ 13 In consideration of the above, an opening margin tm2 smaller than the opening margin tm1 is set. In addition, although the example using two opening margins tm1 and tm2 has been described, three or more opening margins may be set.

The particle beam irradiation apparatus 50 according to the first embodiment sets the opening shape of the collimator 6 (the shape of the opening 74) based on the cross-sectional shape of the tumor (irradiation target 11) in each slice, that is, the irradiation target outer periphery 69. A sufficient dose can be applied to the entire interior of the tumor while suppressing unnecessary dose application outside the tumor three-dimensionally. In addition, when the distance between the tumor (irradiation target 11) and the risk organ (risk target) 13 is short, the particle beam irradiation apparatus 50 according to the first embodiment is not close to the risk organ (risk target) 13. Since the opening margin tm2 smaller than the opening margin tm1 in the part is set, even when the distance between the tumor (irradiation target 11) and the risk organ (risk target) 13 is close, the dose imparted to the tumor (irradiation target 11) and the risk The particle beam 10 can be irradiated by the scanning irradiation method so as to achieve both dose avoidance to the organ (risk target) 13.

The flow chart shown in FIG. 3 is described on the premise of a raster scanning method in which irradiation of the particle beam 10 is not stopped when the particle beam 10 is scanned from the spot 12 to the next spot 12 in the slice. A discrete spot scanning method in which irradiation of the particle beam 10 is temporarily stopped when the particle beam 10 is scanned from one spot 12 to the next spot 12 may be used. FIG. 9 is another flowchart showing the operation of the particle beam irradiation apparatus of FIG. In the case of the discrete spot scanning method shown in FIG. 9, in the slice irradiation procedure of step F05, step F11 (particle beam irradiation temporary stop procedure) of particle beam irradiation suspension is added during the transition from step F06 to step F07. Then, step F12 (particle beam irradiation restarting procedure) for restarting particle beam irradiation is added during the transition from step F07 to step F06.

In FIG. 1, the example in which the collimator opening shape data data1 is generated by the treatment planning device 51 has been described. However, the collimator opening shape data data1 is generated by the opening shape calculation device 53 which is a terminal different from the treatment planning device 51. May be. FIG. 10 is a schematic configuration diagram of another particle beam irradiation apparatus according to Embodiment 1 of the present invention. The particle beam irradiation apparatus 50 in FIG. 10 is different from the treatment planning apparatus 51 in that the collimator opening shape data data1 is input to the collimator information storage unit 32 from the opening shape calculation device 53 which is a terminal. Different from the device 50. The opening shape calculation device 53 includes an opening shape calculation unit 52, and the opening shape calculation unit 52 generates collimator opening shape data data1. The opening shape calculation device 53 determines the collimator opening shape by the opening shape calculation unit 52 based on information such as spot arrangement and tumor shape transmitted from the treatment planning device 51 or a patient information server (not shown), and this collimator opening shape. Is transmitted to the collimator information storage unit 32.

Furthermore, the particle beam irradiation apparatus 50 may have the configuration shown in FIG. FIG. 11 is a schematic configuration diagram of another particle beam irradiation apparatus according to Embodiment 1 of the present invention. An opening shape calculation device 53 in FIG. 11 includes a collimator information storage unit 32 and an opening shape calculation unit 52, and the particle beam irradiation device 50 in FIG. 11 is an example in which the storage unit 3 includes only the spot information storage unit 31. . The control device 4 generates a collimator control signal sig1 based on the collimator opening shape data data1 stored in the spot information storage unit 31 of the opening shape calculation device 53.

1, 10, 11, and 12 have functions realized by the processor 98 and the memory 99 shown in FIG. 13. FIG. 13 is a diagram illustrating a hardware configuration that implements the functional blocks of the opening shape calculation unit illustrated in FIGS. 1, 10, 11, and 12. The opening shape calculation unit 52 is realized by the processor 98 executing a program stored in the memory 99. Further, the plurality of processors 98 and the plurality of memories 99 may execute the above functions in cooperation.

As described above, the particle beam irradiation apparatus 50 according to the first embodiment is a particle beam irradiation apparatus that irradiates the particle beam 10 for each cross section of the irradiation target 11 perpendicular to the reference irradiation axis 60 of the particle beam. The particle beam irradiation apparatus 50 according to the first embodiment includes an energy changing mechanism 9 that changes the energy of the particle beam 10, and the particle beam generating and transporting apparatus 1 that transports and blocks the accelerated particle beam 10, and the particle beam The scanning device 2 that moves the irradiation position (spot 12) for irradiating the irradiation object 11 by deflecting the particle beam 10 transported from the generating and transporting device 1 in two directions perpendicular to the traveling direction, and the reference irradiation axis 60 The collimator 6 has an aperture 74 in the vertical direction, the aperture shape that is the shape of the aperture 74 can be changed, and blocks the passage of the particle beam 10 outside the aperture 74, and information on the aperture shape of the collimator 6 (collimator aperture shape A collimator information storage unit 32 for storing data (data 1), a particle beam generating and transporting device 1 including an energy changing mechanism 9, a scanning device 2 and a control device 4 for controlling the collimator 6. The collimator control signal sig1 sets the opening shape of the collimator 6 based on the opening shape information (collimator opening shape data data1) of the collimator 6 when the control device 4 irradiates the irradiation target 11 with the particle beam 10. Is output to the collimator 6. In the particle beam irradiation apparatus 50 according to the first embodiment, the opening shape of the collimator 6 is set based on the opening shape information (collimator opening shape data data1) of the collimator 6 due to this feature. Scanning irradiation can be performed so as to minimize the dose application to the outside of the tumor while giving a sufficient dose to the whole.

Embodiment 2. FIG.
FIG. 14 is a diagram for explaining a setting example of a collimator opening shape in the collimator of the second embodiment. FIG. 15 is a view for explaining the distribution in the Z direction of the irradiation dose for the spot of FIG. 16 is a diagram for explaining the distribution in the X direction of the irradiation dose for the spot in FIG. 1, and FIG. 17 is a diagram for explaining the distribution in the Y direction of the irradiation dose for the spot in FIG. FIG. 18 and FIG. 19 are diagrams for explaining a problem in the positional relationship between the collimator aperture shape, the irradiation target, and the slice. FIG. 20 is a diagram for explaining the overlap of dose distributions in the X direction by the slices of FIGS. 18 and 19. FIGS. 21 and 22 are diagrams for explaining a specific example of a collimator opening shape setting method in the collimator of the second embodiment. FIG. 23 is a diagram for explaining the collimator opening projected onto the irradiation target slice in FIG. 21 and the projection irradiation target outer periphery projected onto the slice. FIG. 24 is a diagram for explaining overlap of dose distributions in the X direction by a plurality of slices in the collimator of the second embodiment.

As shown in FIGS. 15 to 17, in the scanning irradiation, the irradiation dose distribution for one spot 12 has a sharp peak at the spot position, but the dose distribution has not only one point but also a spatial spread. 15 to 17 are examples of distributions of the irradiation dose with respect to one spot 12 in the X, Y, and Z directions. The vertical axis in FIGS. 15 to 17 is the dose, and the horizontal axes in FIGS. 15 to 17 are the positions in the X, Y, and Z directions, respectively. The positions of the spot 12 in the X direction, the Y direction, and the Z direction are P1x, P1y, and P1z, respectively. In particular, in the Z direction, if the beam traveling direction is the positive direction of the Z axis, the positive direction of the Z axis is called deep, and the negative direction is shallow, the dose distribution is shallower and deeper than the spot. As a result, the dose applied to the side shallower than the spot is not zero. Considering scanning irradiation to a tumor that spreads in three dimensions, the dose given to the shallow part of the tumor is the dose from the spot placed in the shallow part and the dose from the spot placed in the deeper part. It becomes the total value.

The asymmetric dose distribution in the Z direction may cause a problem when the collimator aperture shape is changed for each slice as in the first embodiment. For simplification, an example in which there are only two slices will be described with reference to FIGS. FIGS. 18 and 19 are views of the positional relationship between the collimator 6, the tumor (irradiation target 11), and the slice from the Y direction. There are two slices, slice 61a and slice 61b, and slice 61a is more than slice 61b. It is in a deep position. In addition, the cross section of the tumor in the slice 61a is smaller than the cross section of the tumor in the slice 61b. Therefore, the opening 74a of the collimator 6 when irradiating the slice 61a is set smaller than the opening 74b of the collimator 6 when irradiating the slice 61b. It is assumed that At this time, in the total dose distribution that is the sum of the irradiation doses for the two slices, the distribution in the X direction (total dose distribution 76) at the depth at which the slice 61b exists is transferred to the slice 61b as shown in FIG. And the contribution of the component (dose distribution 75a) in the depth of the slice 61b of the dose distribution due to the irradiation to the slice 61a.

FIG. 20 is a diagram for explaining the dose distribution in the X direction at the depth at which the slice 61b exists. The vertical axis in FIG. 20 is the dose at the depth of the slice 61b, and the horizontal axis in FIG. 20 is the position in the X direction. The position X1 is a projected opening end position on the slice 61b at the end of the opening 74a of the collimator 6 when the slice 61a is irradiated with the particle beam. The position X2 is a projected opening end position on the slice 61b at the end of the opening 74b of the collimator 6 when the slice 61b is irradiated with the particle beam. The ends of the

openings

74a and 74b corresponding to the positions X1 and X2 are the right end of the opening 74a in FIG. 18 and the right end of the opening 74b in FIG. The dose distribution 75a, which is a component at the depth of the slice 61b, in the irradiation dose of the particle beam to the slice 61a is the end of the opening 74a of the collimator 6 when the particle beam is irradiated to the slice 61a due to the shielding effect of the collimator 6. A steep dose gradient is present in the vicinity of the projection opening end position (position X1). On the other hand, since the tumor cross section of the slice 61b is larger than the slice 61a, it is necessary to supplement the dose at a position farther from the position X1 of the dose distribution 75a in order to make the total dose distribution at the depth of the slice 61b closer uniformly. For this reason, the dose distribution 75b of the particle beam irradiation to the slice 61b needs to be a non-uniform distribution that is larger in the vicinity of the edge than in the vicinity of the center.

The collimator opening shape is also set based on the cross section of the tumor in the slice 61b when the slice 61b is irradiated with the particle beam. At this time, a steep dose distribution is formed because of the particle beam irradiation to the slice 61b. At this time, the end of the opening 74b of the collimator 6 is in the vicinity of the projected opening end position (position X2) to the slice 61b and outside the position X1 (positive direction of the X coordinate). In such a case, in the dose distribution 75b of the particle beam irradiation to the slice 61b, the dose gradient in the vicinity of the position X1 and the X1 of the component at the depth of the slice 61b of the dose distribution 75a by the particle beam irradiation to the slice 61a. It is difficult to make the dose gradient near the same steep. Therefore, as shown in FIG. 20, the total dose distribution 76 obtained by adding up the dose distribution 75b and the dose distribution 75a can be a factor that hinders the uniformity in the vicinity of the position X1.

In realistic scanning illumination, the number of slices is greater than two and the contribution from more slices must be taken into account, including the condition that the collimator aperture in the deep slice is smaller than the collimator aperture in the shallow slice In the case of the combined dose distribution in the shallow part of the tumor, there is a possibility that the steep dose gradient near the opening edge in the irradiation of the deep slice and the slow dose gradient in the irradiation of the shallow slice may be added However, in the vicinity of such a position, it may become more difficult to make the total dose distribution uniform.

The above problem can be solved by setting the collimator opening for the deep slice to be the same as or larger than the collimator opening for the shallow slice. A specific example of a collimator aperture shape setting method that solves the above problem will be described with reference to FIGS. 21 and 22. FIG. 21 is a setting example of a collimator opening shape corresponding to a deep slice (slice 61a), and FIG. 22 is a setting example of a collimator opening shape corresponding to a shallow slice (slice 61b). First, a method for setting a collimator aperture shape corresponding to a shallow slice (slice 61b) will be described.

The collimator opening shape corresponding to the shallow slice (slice 61b) is the collimator 6 with respect to the irradiation target outer periphery 69, which is the outer periphery of the cut surface of the slice 61b of the tumor (irradiation target 11), as described with reference to FIG. The shape of the collimator opening is set so that the enlarged shape by adding the opening margin tm matches the projected opening end 68 that is the end of the opening 74b of the collimator 6 projected onto the slice 61b. In FIG. 22, the irradiation target outer peripheral positions Xtb1 and Xtb2 indicate the outer peripheral positions in the X direction on the irradiation target outer peripheral 69, and the projection opening end positions Xepb1 and Xepb2 indicate the end positions in the X direction on the projection opening end 68. ing. The outer peripheral beam path 79b is a path of the particle beam 10 from the scanning starting point P0 to the irradiation target outer peripheral positions Xtb1 and Xtb2, and the outer peripheral beam path 80b is a path of the particle beam 10 from the scanning starting point P0 to the projection opening end position Xepb1 and Xepb2. It is.

Next, a method for setting the collimator aperture shape corresponding to the deep slice (slice 61a) will be described. When setting the collimator aperture shape corresponding to the slice 61a, first, as shown in FIG. 21, the two-dimensional shape projected onto the slice 61a shallower than the cross section of the slice 61a of the tumor (irradiation target 11) is considered. . That is, consider the two-dimensional shape of the projection irradiation outer periphery 81 (see FIG. 23) obtained by projecting the shallow tumor cross section onto the plane of the slice 61a. The projection irradiation target outer periphery 81 is the maximum outer periphery when the irradiation target 11 is viewed from the scanning starting point P0. A projection opening, which is an end of the opening 74a of the collimator 6 projected onto the slice 61a, is a shape obtained by adding a predetermined opening margin tm of the collimator 6 to the two-dimensional shape of the projection target outer periphery 81. The shape of the collimator opening is set so as to coincide with the end 68.

In FIG. 21, the projection irradiation target outer peripheral positions Xtpa1 and Xtpa2 indicate the outer peripheral positions in the X direction of the projection irradiation target outer periphery 81. Projected opening end positions Xepa 1 and Xepa 2 indicate end positions in the X direction at the projected opening end 68. The outer peripheral beam path 79a is a path of the particle beam 10 from the scanning start point P0 to the projection irradiation target outer peripheral positions Xtpa1 and Xtpa2, and the outer peripheral beam path 80a is the path of the particle beam 10 from the scanning start point P0 to the projection opening end position Xepa1 and Xepa2. It is a route.

FIG. 14 is an example in which the collimator mouth shape is determined by the above method when the tumor (irradiation target 11) is spherical. In FIG. 14, the

slice center lines

61a, 61b, 61c, 61d, 61e, and 61f indicating the positions of the six slices, and the

collimator projections

8a, 8b, 8c, 8d, 8e, and 8f of the collimator 6 projected onto the respective slices. showed that. The outer peripheral beam path 79 is a path of the particle beam 10 from the scanning start point P0 toward the projection irradiation target outer periphery 81 in each of the

slices

61a, 61b, 61c. The

slices

61a, 61b, and 61c are slices deeper than the center of the spherical tumor, and the

slices

61d, 61e, and 61f are slices shallower than the center of the spherical tumor. The reference symbol of the outer peripheral beam path is 79 as a whole, and 79a and 79b are used in the case of distinction. When the irradiation target outer periphery 69 of the slice is larger than the irradiation target outer periphery 69 of the slice shallower than the slice, there is no projection irradiation target outer periphery 81 projected onto the slice, and therefore the outer peripheral beam path 79b shown in FIG. Is a beam path to the outer periphery 69 to be irradiated in the slice 61b.

In

slices

61d, 61e, and 61f shallower than the center of the spherical tumor, an enlarged shape by adding an opening margin tm of the collimator 6 to the outer periphery of the cross section (irradiation target outer periphery 69) of the tumor slice, and the opening 74 of the collimator 6 The collimator aperture is set so that the projections on the slices at the ends of the collimator coincide. On the other hand, in

slices

61a, 61b, 61c deeper than the center of the tumor, a cross-section on the XY plane passing through the center of the tumor, that is, a shape having a circle having a radius equal to the radius of the sphere is projected onto the slice (projection irradiation target outer periphery 81 The collimator opening is set so that the shape expanded by adding the opening margin tm of the collimator 6 matches the projection onto the slice of the end of the opening 74 of the collimator 6. With this setting, regardless of which two slices are selected, the collimator aperture shape corresponding to the deep slice is always set to be the same as or wider than the collimator aperture shape corresponding to the shallow slice.

Referring to FIG. 24, the overlap of dose distributions in the X direction due to a plurality of slices in the collimator of the second embodiment will be described. For simplicity, the overlap of dose distributions in the X direction of only two slices will be described. FIG. 24 shows the dose distribution 77b in the X direction at the depth where the slice 61d in FIG. 14 exists, and the contribution component (dose distribution 77a) in the slice 61d of the dose distribution by irradiation to the deep slice 61a. The vertical axis in FIG. 24 is the dose at the depth of the slice 61d, and the horizontal axis in FIG. 24 is the position in the X direction. The position X1 is a projected opening end position on the slice 61d at the end of the opening 74 of the collimator 6 when the particle beam is irradiated onto the slice 61a. The position X2 is the position of the projection opening end portion of the end portion of the opening 74 of the collimator 6 onto the slice 61d at the time of particle beam irradiation to the slice 61d. The dose distribution 77b, which is a component at the depth of the slice 61d, in the irradiation dose of the particle beam to the slice 61d is the end of the opening 74 of the collimator 6 when the particle beam is irradiated to the slice 61d due to the shielding effect of the collimator 6. A steep dose gradient is present in the vicinity of the projection opening end position (position X2) to the slice 61d. On the other hand, the dose distribution 77a which is a component at the depth of the slice 61d in the irradiation dose of the particle beam to the slice 61a is a uniform distribution in the irradiation target 11, and is slow from the irradiation target outer periphery 69 to the position X2. It is a distribution that decreases. In the dose distribution 77a of FIG. 24, the uniform part is inside the irradiation target 11, and the part where the dose starts to decrease corresponds to the outer periphery 69 of the irradiation target. Compared with the total dose distribution 76 shown in FIG. 20, the total dose distribution 78 obtained by adding the dose distribution 77a and the dose distribution 77b does not greatly increase or decrease, and the uniformity of the distribution can be improved.

In the particle beam irradiation apparatus 50 according to the second embodiment, the shape of the opening 74 of the collimator 6 corresponding to the deep slice is set to be the same as or wider than the shape of the collimator opening corresponding to the shallow slice. Since the steep dose gradient in the vicinity of the opening end in the irradiation and the slow dose gradient in the irradiation to the shallow slice are not added together, the combined dose distribution can be made uniform.

In the second embodiment, the case where the opening margin tm is one has been described. However, the two opening margins tm1 and tm2 described in FIG. 8 may be set. Three or more opening margins may be set. In this case, the combined dose distribution to the tumor (irradiation target 11) is uniform, and even when the distance between the tumor (irradiation target 11) and the risk organ (risk target) 13 is short, the tumor (irradiation target 11) The particle beam 10 can be irradiated by the scanning irradiation method so as to achieve both dose application and avoidance of dose application to the risk organ (risk target) 13.

Embodiment 3 FIG.
In the first and second embodiments, the collimator 6 has been described on the assumption that the particle beam 10 is always blocked except for the opening 74. That is, the thickness of the collimator 6 in the Z direction is based on the premise that the maximum energy particle beam 10 that can be generated and transported in the particle beam generating and transporting apparatus 1 can be completely stopped. In the present embodiment, it is not always necessary to have a thickness capable of completely stopping the particle beam 10 having the maximum energy, and it is possible to completely stop the particle beam 10 having a predetermined energy or less that can be generated and transported. It may be a thickness that can be made.

The cause of the spread in the horizontal direction (XY direction) of the dose distribution given by the particle beam 10 to the irradiation object 11 is roughly classified into two. The first factor (first factor) is the lateral spreading component of the particle beam 10 existing at the time of generation in the particle beam generating and transporting device 1, and the component downstream of the particle beam irradiation device 50 (scanning device 2). , A dose monitor 5 or the like) that occurs before passing through the collimator 6, such as scattering due to collision with a component on the downstream side of the particle beam irradiation device 50. The second factor (second factor) mainly passes through the collimator 6 such as multiple scattering due to collision with the irradiation object 11 when the particle beam 10 travels inside the irradiation object (patient body) 11. It is the spread that occurs after. Although the role of the collimator 6 in the present invention is to invalidate or suppress the influence of the first factor, the collimator 6 cannot exert the effect against the second factor.

When the contribution of the first factor and the second factor to the lateral spread of the particle beam 10 without the collimator 6 is compared, generally, when the energy of the particle beam 10 is low, the contribution of the first factor is large and the particle When the energy of the line 10 is high, the contribution of the second factor is large. This is because the higher the energy of the particle beam 10, the longer the distance traveled inside the irradiation object 11, and thus more influence of multiple scattering due to the collision with the irradiation object 11. Therefore, in many cases, as shown in FIG. 6, by using the collimator 6, the spread of the dose in the lateral direction is improved from the dose distribution 66 to the dose distribution 65, but there is energy of the particle beam 10. When the value is higher than a certain value, as shown in FIG. 25, even if the collimator 6 is used, a large distribution improvement may not be seen. FIG. 25 is a diagram for explaining the X-direction distribution of the dose given to the slice to be irradiated when the energy of the particle beam is high. In FIG. 25, the vertical axis represents the dose, and the horizontal axis represents the position in the X direction. The dose distribution 65a is a dose distribution when the collimator 6 is present, and the dose distribution 66a is a dose distribution when the collimator 6 is not present. The broken line 67 is the same as FIG.

The spread of the particle beam 10 in the lateral direction (lateral spread length) is reduced, for example, from the end of the irradiation target 11 (portion indicated by the broken line 67) to the inner half of the irradiation target 11 (broken line 82). Is defined as a distance Xp. In this case, the relationship between the energy of the particle beam 10 and the spread of the dose in the lateral direction is as shown in FIG. FIG. 26 is a diagram showing the relationship between the energy of the particle beam and the lateral spread length of the dose. In FIG. 25, the lateral extension length when the collimator 6 is provided is Xp1, and the lateral extension length when the collimator 6 is not provided is Xp2. In FIG. 26, the vertical axis represents the lateral spread length of the dose, and the horizontal axis represents the energy of the particle beam. The lateral extension length when the collimator 6 is not used is a characteristic 83, and the lateral extension length when the collimator 6 is used is a characteristic 84.

When the energy of the particle beam 10 is lower than the energy value Ec shown in FIG. 26, the lateral spread (lateral spread length Xp) can be remarkably suppressed by using the collimator 6. However, when the energy of the particle beam 10 is equal to or higher than the energy value Ec, the benefit of using the collimator 6 is not so great. For example, the energy value Ec is a value at which the difference between the value of the characteristic 83 and the value of the characteristic 84 is 5% or less. Therefore, when the energy of the particle beam 10 is greater than or equal to the energy value Ec, the opening 74 of the collimator 6 may be set to be fully opened. Here, “full open” refers to a setting in which the opening area possible is widest in the drive range of each leaf 7 of the collimator 6. In such an operation, it is sufficient that the collimator 6 has a thickness in the Z direction that can completely stop the particle beam 10 whose energy is the energy value Ec. The collimator 6 can be manufactured with a smaller thickness than the thickness that can completely stop 10, and the entire apparatus of the particle beam irradiation apparatus 50 can be reduced in weight and size.

Although the example in which the aperture 74 of the collimator 6 is fully opened when the energy of the particle beam 10 is equal to or higher than the energy value Ec has been shown, for example, the collimator 6 is sufficiently more than the maximum scanning region of the particle beam 10 even if not fully opened. Needless to say, if the aperture 74 is wide and the particle beam 10 does not come into contact with the leaf 7 of the collimator 6, a dose distribution similar to that when fully opened can be obtained.

It should be noted that the present invention can be combined with each other within the scope of the invention, and each embodiment can be modified or omitted as appropriate.

DESCRIPTION OF SYMBOLS 1 ... Particle beam generation transport apparatus, 2 ... Scanning device, 4 ... Control apparatus, 6 ... Collimator, 9 ... Energy change mechanism, 10 ... Particle beam, 11 ... Irradiation object, 12 ... Spot (irradiation position), 13 ... Risk organ (Risk object), 32 ... collimator information storage unit, 50 ... particle beam irradiation device, 60 ... reference irradiation axis, 74, 74a, 74b ... opening, data1 ... collimator opening shape data, sig1 ... collimator control signal, tm, tm1, tm2 ... opening margin, Am1, Am2 ... margin area

Claims

A particle beam irradiation apparatus that irradiates the particle beam for each cross section of an irradiation object perpendicular to the reference irradiation axis of the particle beam,
A particle beam generating / transporting device having an energy changing mechanism for changing the energy of the particle beam and transporting and blocking the accelerated particle beam, and a traveling direction of the particle beam transported from the particle beam generating / transporting device A scanning device that moves the irradiation position irradiated to the irradiation target by deflecting in two directions perpendicular to the aperture, and an opening shape in the direction perpendicular to the reference irradiation axis, and the shape of the opening is changed A collimator capable of blocking the passage of the particle beam outside the opening, a collimator information storage unit for storing information on the opening shape of the collimator, the particle beam generating and transporting device including the energy changing mechanism, and the scanning And a control device for controlling the collimator,
The control device outputs a collimator control signal for setting the opening shape of the collimator to the collimator based on information on the opening shape of the collimator when irradiating the irradiation target with the particle beam. A characteristic particle beam irradiation apparatus.
The collimator information storage unit stores information on the opening shape of at least two of the collimators,
When the energy of the particle beam is changed, the control device outputs a collimator control signal for setting the aperture shape of the collimator to the collimator based on information on the aperture shape of the collimator corresponding to the energy The particle beam irradiation apparatus according to claim 1.
The collimator information storage unit stores information on the opening shape of at least two collimators in association with energy of the particle beam,
When the energy of the particle beam is changed, the control device outputs a collimator control signal for setting the aperture shape of the collimator to the collimator based on information on the aperture shape of the collimator corresponding to the energy The particle beam irradiation apparatus according to claim 1.
4. The particle beam irradiation according to claim 2, wherein the opening shape of the collimator is a shape expanded by adding a predetermined margin to the shape of the cross section of the irradiation target. 5. apparatus.
When there is a risk target to avoid the irradiation of the particle beam as much as possible when irradiating the irradiation target with the particle beam,
The opening shape of the collimator is a shape expanded by adding a predetermined margin to the shape of the cross section of the irradiation target, and based on the position of the risk target in the cross section of the irradiation target The margins are different,
4. The particle beam irradiation apparatus according to claim 2, wherein a margin of a region near the risk target in the opening is smaller than a margin of other regions in the opening.
The opening shape of the collimator when the energy of the particle beam is high is set to be the same as or wider than the opening shape of the collimator when the energy of the particle beam is lower. The particle beam irradiation apparatus according to any one of claims 2 to 5, wherein the particle beam irradiation apparatus is characterized.
The opening shape of the collimator is changed to a shape wider than the maximum scanning region of the particle beam when the energy of the particle beam is a predetermined value or more. 2. The particle beam irradiation apparatus according to item 1.