Particle beam treatment system, treatment planning device, and range modulator system

Abstract

To provide a particle beam treatment system, a treatment planning device, and a range modulator system, capable of expressing a FLASH effect in scanning particle beam treatment and inhibiting dose concentration from being reduced by reduction in the number of layers.SOLUTION: A particle beam treatment system comprises: an accelerator system 104 and an irradiation nozzle 106 for irradiating a target 209 with a particle beam with a plurality of pieces of energy; range modulators 306, 601, and wings 704 for extending a width of a black peak of the particle beam; and a treatment planning device 111 that separates target 209 into a plurality of sub regions 1102A, 1102B and, for each of the sub regions 1102A, 1102B, determines the number of layers dividing the target 209 in a direction of travel of the particle beam, energy of the particle beam for each layer, types of the range modulators 306, 601, and the wings 704, and an irradiation position and an irradiation amount of the particle beam, so as to obtain a target dose set for the target 209.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to a particle beam therapy system, a treatment planning device, and a range modulator system for treating cancer by irradiating a cancer-affected area with a particle beam. [Background technology]

[0002] Patent document 1 states, "A radiation therapy system includes an accelerator that generates a particle beam and a beam transport system. The accelerator and beam transport system guide the beam on a path and to a nozzle that is operable to direct the beam toward a target. The nozzle includes a scanning magnet that is operable to steer the beam toward different locations within the target, and also includes a beam energy adjuster configured to adjust the beam, for example, by placing materials of different thicknesses in the path of the beam to affect the energy of particles in the beam." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 11529532 Summary of the Invention [Problem to be solved by the invention]

[0004] Particle beam therapy is a treatment that aims to eradicate tumors and relieve pain by irradiating tumors inside the patient's body with particle beams such as proton beams or heavy particle beams and delivering a dose. Compared to X-rays, in which the dose delivered to the patient's body slowly decays with depth, particle beams form a dose peak (called the Bragg peak) at a certain depth determined by the particle energy. Therefore, it has the advantage that it is easy to deliver a concentrated dose to the tumor.

[0005] In general, in particle beam therapy, particles (hereinafter referred to as beams) accelerated in an accelerator system consisting of a linear accelerator, cyclotron, synchrotron, etc. are transported to an irradiation nozzle and irradiated onto the tumor.

[0006] There are two main beam irradiation methods: the passive method and the scanning method.

[0007] In the passive method, the beam shape is adjusted to match the tumor using a scatterer that expands the beam in a direction perpendicular to the direction of propagation (hereafter referred to as the lateral direction) and a range modulator that expands the Bragg peak in the direction of propagation to form a spread-out Bragg peak (SOBP).

[0008] On the other hand, the scanning method is a method in which the direction of a thin beam called a pencil beam is adjusted by a scanning magnet while changing the beam energy, i.e. the depth of the Bragg peak, to sequentially irradiate minute areas (hereafter referred to as spots) arranged throughout the tumor. A surface made up of spots irradiated with a beam of a single energy is called a layer. Advantages of the scanning method include the ease of forming more complex dose distributions and the small effect of beam loss in scattering media and device activation.

[0009] In recent years, ultra-high dose rate radiation therapy, so-called FLASH therapy, has been attracting attention. In FLASH therapy, irradiation is performed at a dose rate of approximately 40 Gy / s or more, which is several thousand times higher than the conventional dose rate of about 1 Gy / min, and it is expected that the so-called FLASH effect will be expressed, which maintains antitumor effects while reducing side effects on normal tissues. Therefore, it is thought that a very high therapeutic effect can be obtained by combining scanning particle therapy, which has high dose concentration, and FLASH therapy.

[0010] However, because the scanning method requires time for beam energy changes and scanning, it is highly likely that the dose rate required to manifest the FLASH effect cannot be achieved, especially in the treatment of large tumors.

[0011] Specifically, in the case of a cyclotron or synchrocyclotron, the energy is attenuated by a range shifter after extraction from the accelerator, whereas in the case of a synchrotron, the energy can be selected at the time of extraction because it is an accelerator with variable energy.

[0012] In either case, the energy change requires a time of tens to hundreds of milliseconds. Although the beam scanning time is generally short compared to the energy change, the time scale is not negligible in cases where the tumor size is large in the lateral direction.

[0013] Patent Document 1 discloses a method of forming a dose distribution in the depth direction by using a range shifter and a range modulator for each sub-region divided into several groups in the horizontal direction. Since the range modulator forms an SOBP that matches the target, the energy change time is suppressed and irradiation of the sub-region can be completed in a short time. In addition, by dividing the sub-regions and irradiating them in sequence, high dose rate treatment is possible in each region even if the horizontal area of ​​the irradiation range is large.

[0014] In Patent Document 1, the dose distribution is expanded in the depth direction using only a range modulator, so when applied to a large-volume tumor, the maximum energy attenuation in the range modulator is large, resulting in a significant decrease in dose rate.

[0015] The present invention has been made in consideration of the above circumstances, and discloses a particle beam therapy system, a treatment planning device, and a range modulator system that can achieve the FLASH effect in scanning particle beam therapy and suppress a decrease in dose concentration due to a reduction in the number of layers. [Means for solving the problem]

[0016] The present invention includes a plurality of means for solving the above-mentioned problems. For example, the present invention includes an irradiation system for irradiating an irradiation target with particle beams of a plurality of energies, a plurality of range modulators for expanding the width of the Bragg peak of the particle beam, and a planning device for dividing the irradiation target into a plurality of sub-areas and determining the number of layers for dividing the irradiation target in the traveling direction of the particle beam, the energy of the particle beam for each layer, the type of the range modulator, and the irradiation position and irradiation amount of the particle beam for each sub-area so as to achieve a target dose set for the irradiation target. Effect of the Invention

[0017] According to the present invention, the beam is efficiently used to improve the FLASH effect in scanning particle beam therapy, while suppressing the decrease in dose concentration due to the reduction in the number of layers, thereby improving the biological effect in particle beam therapy. The problems, configurations and effects other than those described above will be made clear by the following description of the embodiments. [Brief description of the drawings]

[0018] [Figure 1] 1 is a diagram showing an overall configuration of a particle beam therapy system according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing a configuration of an irradiation nozzle in the first embodiment of the present invention. [Diagram 3] 1 is a diagram showing an example of the configuration of a range modulation system in a first embodiment of the present invention, viewed from the Y direction. [Figure 4] FIG. 2 is a diagram showing a unit structure of a range modulator according to the first embodiment of the present invention. [Diagram 5] FIG. 2 is a diagram showing an example of a range modulation system configuration in the first embodiment of the present invention, viewed from the Z direction. [Figure 6] FIG. 4 is a diagram showing another example of the configuration of the range modulation system in the first embodiment of the present invention. [Figure 7] FIG. 2 is a diagram showing a configuration of a range modulation wheel in the first embodiment of the present invention. [Figure 8]FIG. 1 is a diagram showing the configuration of a treatment planning device in a first embodiment of the present invention. [Figure 9] 1 is a flowchart showing an overall flow of particle beam therapy in a first embodiment of the present invention. [Figure 10] 4 is a flowchart showing details of a treatment planning flow in the particle beam therapy flow in the first embodiment of the present invention. [Figure 11] 1 is a flowchart showing details from preparation for sub-region irradiation to completion of irradiation in a particle beam therapy flow according to the first embodiment of the present invention. [Figure 12] FIG. 4 is a diagram showing a method of dividing sub-regions in the first embodiment of the present invention. [Figure 13] FIG. 1 is a diagram showing changes in dose distribution before and after optimization of a layer range modulator in Example 1 of the present invention. [Figure 14] 10 is a flowchart showing details of a treatment planning flow in a particle beam therapy flow according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, embodiments of the particle beam therapy system, the treatment planning device, and the range modulator system of the present invention will be described with reference to the drawings. In the drawings used in this specification, the same or similar reference numerals are used for the same or corresponding components, and the repeated description of these components may be omitted.

[0020] In the present invention, particle beam therapy is carried out using a scanning method. The type of particle beam may be a proton beam or a heavy particle beam such as a helium beam or a carbon beam.

[0021] <Example 1> A particle beam therapy system, a treatment planning device, and a range modulator system according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 13. FIG.

[0022] First, the overall configuration of a particle therapy system will be described with reference to Fig. 1. Fig. 1 is a diagram showing the overall configuration of a particle therapy system according to the present embodiment.

[0023] The particle beam therapy system 101 shown in Fig. 1 is a system for irradiating a beam 103 to a target 209 (see Fig. 2 etc. described later) in a patient 102, and as shown in Fig. 1, includes an accelerator system 104, a beam transport system 105, an irradiation nozzle 106, a treatment table 107, an overall control device 108, an accelerator system / beam transport system control device 109, an irradiation control device 110, and a treatment planning device 111. Of these, the accelerator system 104 and the irradiation nozzle 106 constitute an irradiation system that irradiates the target 209 with particle beams of multiple energies.

[0024] The accelerator system 104 is a device that generates and accelerates the beam 103. In Fig. 1, an example of the accelerator including the injector 112, the synchrotron accelerator 113, and the ion source 114 is shown, but other types of devices that accelerate particle beams, such as a cyclotron accelerator or a linear accelerator, may be used instead.

[0025] The beam transport system 105 is a group of devices that transport the beam 103 accelerated by the accelerator system 104 to the irradiation nozzle 106 that irradiates the beam 103 to the target 209 in the patient 102, and connects the accelerator system 104 to the irradiation nozzle 106. The beam transport system 105 has a bending electromagnet 115 and a rotating gantry, but may also be a fixed irradiation port. Also, the beam transport system 105 may be omitted and the accelerator system 104 may be directly connected to the irradiation nozzle 106.

[0026] The irradiation nozzle 106 is a container equipped with a group of devices that adjust the beam 103 transported from the beam transport system 105, irradiate the target 209, and measure the characteristics of the irradiated beam 103. The detailed configuration of the irradiation nozzle 106 will be described later with reference to FIG.

[0027] The overall control device 108 is connected to a treatment planning device 111, an accelerator system / beam transport system control device 109, an irradiation control device 110, and a treatment table 107, and controls the operation of each device based on the prescription transferred from the treatment planning device 111.

[0028] The accelerator system / beam transport system controller 109 controls the operation of each device constituting the accelerator system 104 and the beam transport system 105 based on instructions from the overall controller 108 .

[0029] The irradiation controller 110 controls the operation of each device constituting the irradiation nozzle 106 based on instructions from the overall controller 108. The irradiation controller 110 also processes measurement results transmitted from each monitor of the irradiation nozzle 106 and transfers them to the overall controller 108.

[0030] The treatment planning device 111 creates data (hereinafter, prescription) that specifies the energy, position, dose and sequence of the irradiated beam, or parts of these, based on internal images of the patient's affected area and surrounding beam data including the dose distribution and biological effects of the beam, and pre-set treatment planning parameters.

[0031] The above process of creating a prescription by the treatment planning device 111 is called a treatment plan. The detailed configuration of the treatment planning device 111 will be described later with reference to Fig. 8, but in the treatment planning device 111 of this embodiment, the target 209 is divided into a plurality of sub-regions 1102A and 1102B, and the number of layers into which the target 209 is divided in the traveling direction of the particle beam, the energy of the particle beam for each layer, the type of the range modulators 306 and 601 and the blades 704, and the irradiation position and irradiation amount of the particle beam are determined for each of the sub-regions 1102A and 1102B so as to achieve a target dose set for the target 209. Here, it is preferable that the upper limit of the number of layers is determined in advance based on a biological effect.

[0032] The overall controller 108, the accelerator system / beam transport system controller 109, the irradiation controller 110, and the treatment planning system 111 each have a CPU and a memory connected to the CPU.

[0033] The control process for the operations to be executed may be integrated into one program, or may be divided into multiple programs, or may be a combination of these.

[0034] Some or all of the programs held by each device may be implemented by dedicated hardware or may be modularized. Furthermore, the various programs may be installed in each device from a program distribution server or an external storage medium.

[0035] Furthermore, each device may be an independent device connected to a wired or wireless network, or two or more devices may be integrated together.

[0036] The treatment table 107 is a bed on which the patient 102 is placed. The treatment table 107 can move in three orthogonal axial directions and can also move in so-called six axial directions, rotating around each of the axes, based on instructions from the overall control device 108. By these movements and rotations, the position of the patient 102, i.e., the target 209, can be moved to a desired position.

[0037] Next, a detailed configuration of the irradiation nozzle 106 will be described with reference to Fig. 2. Fig. 2 is a diagram showing the configuration of the irradiation nozzle 106 in the case where the scanning method is assumed.

[0038] Scanning magnets 201A and 201B, a dose monitor 202, a position monitor 203, and a range modulation system 204 are arranged inside the irradiation nozzle 106. In addition, a range shifter 205 may be installed as necessary.

[0039] The irradiation controller 110 is connected to a range modulation system 204 , a dose monitor signal processing system 206 , a position monitor signal processing system 207 , and a scanning magnet controller 208 .

[0040] The scanning magnets 201A and 201B deflect the beam 103 by the magnetic field they generate. Since the scanning magnets 201A and 201B deflect the beam in directions perpendicular to each other, the beam 103 is scanned in two dimensions and irradiated onto a target 209 in the patient 102. When treating a cancer patient, the target 209 represents an area obtained by adding a margin (a margin area that takes into account an error in the irradiation position) to the tumor.

[0041] The range modulation system 204 is used to expand the dose distribution in the beam travel direction. The detailed configuration and operation will be described later. The range shifter 205 can be inserted to adjust the penetration depth of the beam 103.

[0042] The dose monitor 202 is a monitor for measuring the dose rate of the irradiated beam 103, and in turn the dose, and transmits an output of the dose monitor 202 having a magnitude corresponding to the dose rate to a dose monitor signal processing system 206. The dose monitor signal processing system 206 processes the dose monitor output input from the dose monitor 202, and outputs it to the irradiation controller 110 as a signal representing a dose. The irradiation controller 110 calculates the irradiated dose based on the dose signal input from the dose monitor signal processing system 206.

[0043] The position monitor 203 is a monitor for measuring the position and size of the irradiated beam 103. The output of the position monitor 203 is input to a position monitor signal processing system 207. The position monitor signal processing system 207 processes the position monitor output and outputs it to the irradiation controller 110 as a signal representing the position and size. The irradiation controller 110 calculates the position and size of the irradiated beam based on the position and size signal input from the position monitor signal processing system 207.

[0044] Next, the detailed configuration of range modulation system 204 will be described with reference to FIGS.

[0045] 3 is a diagram showing an example of the configuration of the range modulation system 204. The three axes in the diagram are an X-axis 301, a Y-axis 302, and a Z-axis 303, where the Z-axis represents the traveling direction of the beam 103, and the X and Y-axes represent two directions parallel to the horizontal plane (hereinafter, the XY plane) and perpendicular to each other.

[0046] The range modulation system 204 is a mechanism in which at least two types of range modulators 306 of different shapes are arranged in a direction perpendicular to the direction of travel of the particle beam in order to expand the width of the Bragg peak of the particle beam, and which is movable at least in the vertical direction, and is composed of, for example, a modulation system wall 304, a modulator fixing mechanism 305, and a range modulator 306.

[0047] The modulator fixing mechanism 305 can move or expand in either or both directions of the X-axis 301 and the Y-axis 302 to enable the range modulator 306 to move on the trajectory of the particle beam when irradiating the target 209 with particle beams of multiple energies, and has the function of fixing the range modulator 306 at a specified position in the XY plane. For example, it can be a ball screw and its drive mechanism, but various known configurations capable of realizing the above-mentioned functions can be adopted.

[0048] The modulator fixing mechanism 305 is fixed to the modulation system wall 304 on one side and supports a range modulator 306 on another side. A single range modulator 306 may be supported by two or more modulator fixing mechanisms 305, or may be supported by a single modulator fixing mechanism 305.

[0049] The range modulator 306 is a resin or metal structure that has multiple parts of different shapes and has different thicknesses depending on the position in the XY plane. The beam energy absorbed varies depending on the position where the beam passes, and the beam after passing contains a mixture of particles with multiple energies, forming an SOBP with a Bragg peak whose width is expanded in the beam propagation direction.

[0050] The range modulator 306 has a unit structure 401 as shown in Fig. 4. The unit structure is made up of n ridges, where n is a natural number, and the ridge i (i = 1, ..., n) has a ridge width 402 in the X-axis 301 direction of w i , the ridge thickness 403 in the Z-axis direction is t i An arbitrary SOBP width can be formed by adjusting the ridge width 402 and ridge thickness 403 and repeating the unit structure in the XY plane. Note that the ridge thickness may also be variable in the Y-axis 302 direction.

[0051] Fig. 5 is a schematic diagram of the range modulation system 204 in Fig. 3 as viewed from the Z-axis 303 direction. The range modulator 306 is composed of a combination of two or more modulator elements 501 (a total of four modulator elements 501A, 501B, 501C, and 501D in Fig. 5) having different unit structures 401. By controlling the modulator fixing mechanism 305 according to the beam irradiation position, the beam 103 passes through any of the modulator elements 501, so that the SOBP width has a degree of freedom corresponding to the number of modulator elements 501.

[0052] The range modulation system only needs to have a function that gives two or more degrees of freedom to the SOBP width by mechanical control, and can have a configuration as shown in Figures 6 and 7 other than the configuration shown in Figure 3. This will be explained below.

[0053] In the example of range modulation system 204A in Figure 6, three range modulators 601A, 601B, 601C with different unit structures 401 and two or more modulator fixing mechanisms 602A, 602B, 602C that can move each of the range modulators 601A, 601B, 601C on the trajectory of the particle beam when irradiating the target 209 with particle beams of multiple energies are arranged in the Z-axis 303 direction.

[0054] At least two types of range modulators 601A, 601B, 601C of different shapes are arranged in a direction perpendicular to the direction of travel of the particle beam, and are capable of moving at least in the perpendicular direction; at least two types of range modulators 601A, 601B, 601C of different shapes are arranged in the direction of travel of the particle beam, and are also capable of moving at least in a direction perpendicular to the direction of travel.

[0055] By controlling each of the modulator fixing mechanisms 602A, 602B, and 602C, it is possible to arbitrarily select whether or not the beam 103 passes through each of the range modulators 601A, 601B, and 601C. Therefore, in the example of Fig. 6, the SOBP width has 3 x 3 = 9 degrees of freedom. The number of range modulators 601A, 601B, and 601C is not limited to three, and may be two or more.

[0056] Figure 7 shows a conceptual diagram of a range modulation wheel. The range modulation wheel 701 shown in Figure 7 is composed of an outer wall 702, a rotation axis 703, and multiple blades 704 of different shapes fixed between them to expand the width of the Bragg peak of a particle beam. This range modulation wheel 701 also has at least two or more types of blades 704 of different shapes arranged in a direction perpendicular to the traveling direction of the particle beam, and is capable of moving at least in the perpendicular direction.

[0057] The shape of the wing 704 is similar to the unit structure 401 in Fig. 4, and multiple resins or metals with different widths and thicknesses are arranged parallel to the rotation direction of the rotating shaft 703. By arranging a range modulation wheel 701 so that the beam passes through the wing 704 and rotating it around the rotating shaft 703 by a motor (not shown in the figure), the thickness of the wing 704 through which the beam passes during irradiation changes, resulting in a mixture of particles of multiple energies. Therefore, by adjusting the shape of the wing 704, any SOBP width can be formed.

[0058] This motor serves as a modulator fixing mechanism that can move the wing 704 onto the trajectory of the particle beam when irradiating the target 209 with particle beams of multiple energies.

[0059] As in Figures 3 and 6, the SOBP width can be made variable depending on the position of the range modulation wheel in the XY plane, or range modulation wheels with different shapes can be arranged in the Z-axis 303 direction and the wheel to be used can be selected, thereby giving freedom to the SOBP width.

[0060] Next, a detailed configuration of the treatment planning system 111 will be described with reference to Fig. 8. Fig. 8 is a diagram showing the configuration of the treatment planning system 111.

[0061] The treatment planning device 111 is configured as a computer system having, for example, a CPU 801 , a memory 802 , a storage device 803 , a communication interface 804 , and a user interface (UI) device 805 .

[0062] The treatment planning device 111 of this embodiment divides the target 209 into a plurality of sub-regions 1102A and 1102B, and determines the number of layers into which the target 209 is divided in the traveling direction of the particle beam, the energy of the particle beam for each layer, the range modulators 306 and 601, the type of the blade 704, and the irradiation position and irradiation amount of the particle beam for each sub-region 1102A and 1102B so as to achieve a target dose set for the target 209. Details will be described later.

[0063] The storage device 803 is composed of, for example, a flash memory device, a hard disk drive (HDD), etc., and stores computer programs such as an operating system (OS) 806, a dose optimization program 807, a sub-region division program 808, and a layer range modulator optimization program 809, as well as beam data 810 such as the beam size in water and the distribution of the applied dose for each depth. The beam data 810 has values ​​corresponding to each degree of freedom of the range modulator.

[0064] The CPU 801 reads out various programs 807, 808, and 809 stored in the storage device 803 into the memory 802 and executes them, thereby realizing the function of the treatment planning device 111.

[0065] The communication interface 804 is a device for communicating with the overall control device 108. The UI device 805 is a device for exchanging information with a user (hereinafter, referred to as a doctor) who uses the treatment planning device 111, and includes an information output device and an information input device.

[0066] This concludes the detailed description of the configuration and each device of the particle therapy system 101. Hereinafter, the operation procedure of the system in the first embodiment will be described.

[0067] The procedure of treatment by the particle beam therapy system 101 will be described with reference to Fig. 9. Fig. 9 is a flowchart of the particle beam therapy.

[0068] In general, in particle beam therapy, fractionated irradiation is performed in which the target dose is divided into several doses. This is to prevent normal tissue from being damaged by a high dose being given at one time. In this embodiment, a treatment in which the target dose is irradiated in 30 days is specifically assumed. In FLASH therapy, it is assumed that the number of fractions is smaller than that of conventional therapy, but the number of fractions and the amount of irradiation do not affect the effect of the present invention, and the number of fractions may be one, that is, the entire dose may be irradiated at one time. In addition, the fraction unit does not need to be one day, and one day of treatment may be divided into multiple treatments.

[0069] 9, when treatment starts each day (step S901), first, the treatment planning device 111 executes a treatment plan (step S902). A detailed procedure of the treatment plan will be described with reference to FIG.

[0070] First, the treatment planning device 111 reads in-vivo images of the patient's affected area and the surroundings captured by X-ray CT or the like via the communication interface 804. Next, based on the in-vivo images displayed on the UI device 805, the doctor extracts the contours of the tumor and risk organs, and adds a predetermined margin to these contours to determine the contours of the target 209 and risk organs (step S1001).

[0071] Next, the treatment planning device 111 sets the target dose and irradiation direction for the target 209 and the organ at risk (step S1002). The target dose and irradiation direction are input by the doctor via the UI device 805. Note that the input of the irradiation direction may be omitted and may be automatically determined in the next irradiation optimization calculation.

[0072] Next, the treatment planning system 111 calls the dose optimization program 807 and performs dose optimization calculations to provide a target dose (step S1003).

[0073] The dose optimization calculation is performed by iteratively calculating the dose that minimizes the objective function F(x), which is a function of the vector x that represents the pencil beam dose corresponding to each irradiation position, as shown in the following equation (1).

[0074]

number

[0075] In formula (1), Dltarget and DlOAR are the target doses at calculation point l in the target and organ at risk, respectively, and dl(x) represents the dose to be delivered to calculation point l by irradiation determined by vector x. wtarget and wOAR correspond to the weights of each term in optimization and are values ​​input by the doctor. θ(x) is a step function that is 1 when x≧0 and 0 when x<0.

[0076] In this optimization, there is no restriction on the number of layers, and layers corresponding to all energies that can be irradiated by the particle beam therapy system 101 may be used. In addition, there is no freedom in the range modulator, and dose calculation is performed using beam data of a beam that does not pass through a range modulator or a beam that passes through an arbitrary single range modulator.

[0077] Next, the treatment planning system 111 calls the subregion division program 808, and divides the target 209 into a plurality of subregions in the XY plane based on the optimized vector x (step S1004). In this manner, the treatment planning system 111 can first determine the irradiation position and dose of the particle beam, and then divide the subregions 1102A and 1102B based on the dose.

[0078] An example of a division method when a synchrotron is used as an accelerator will be described with reference to Fig. 11. Fig. 11 shows a target 209 as viewed from the Z-axis direction, and each white circle represents a beam irradiation position, that is, a spot 1101.

[0079] First, the treatment planning system 111 sets an upper limit of the irradiation dose of the sub-region according to the performance of the accelerator system 104. In a synchrotron, there is an upper limit to the number of particles that can be accelerated at one time, and after all accelerated particles have been extracted, the beam is stopped for several seconds before being re-extracted. In this embodiment, since the objective is to complete irradiation of the sub-region in the shortest possible time, it is necessary to prevent re-acceleration of the beam during irradiation of the sub-region.

[0080] Therefore, the sub-regions 1102A, 1102B are divided based on the number of particles accelerated in the synchrotron that constitutes the accelerator system 104 and the irradiation nozzle 106. Specifically, the upper limit of the irradiation dose to a single sub-region is determined by converting the upper limit of the number of particles accelerated in the synchrotron into an irradiation dose, and a particle beam is irradiated to each of the sub-regions 1102A, 1102B.

[0081] Next, the treatment planning system 111 determines an irradiation start spot. The irradiation start spot may be determined by a doctor, but may also be automatically selected as the spot with the smallest X and Y coordinates (the spot at the top left in FIG. 11).

[0082] Next, the treatment planning device 111 divides the sub-regions. The irradiation doses of the spots are added in ascending order of distance in the XY plane based on the irradiation start spot, and the region including the spot group selected just before the upper limit of the irradiation dose is exceeded is set as the sub-region 1102A. However, the selection order of the spots is not limited to the above, and the selection order may be determined using other algorithms.

[0083] After that, the irradiation order of the spots included in the sub-region 1102A is determined.

[0084] As an example of a method for determining the order of spot irradiation, there is a method of repeating the process of selecting all spots having the same Y coordinate as the irradiation start spot in order of proximity to the X coordinate, and then selecting the spots having the closest Y coordinate to the last selected spot in order of proximity to the X coordinate, as shown as irradiation order 1103 in Fig. 11. However, the method for determining the order of irradiation is not limited to the above, and for example, the spots may be selected in order of proximity to the irradiation start spot.

[0085] Next, the treatment planning system 111 selects one spot adjacent to the sub-region 1102A as the next irradiation start spot, and executes the same procedure to create the sub-region 1102B and determine the irradiation order. The above procedure is repeated until all spots are included in one of the sub-regions, and the division of the sub-regions is completed.

[0086] The upper limit on the size of the sub-region is not limited to the upper limit on the dose based on the number of accelerated particles. For example, in a cyclotron, which can extract a quasi-continuous beam, the beam does not stop for several seconds, unlike in a synchrotron. In this case, the irradiation time determined by the beam intensity and beam scanning speed becomes a constraint on the sub-region.

[0087] Therefore, when the accelerator system 104 is composed of a cyclotron, the division of the sub-regions 1102A, 1102B is performed based on the maximum beam intensity in the cyclotron or the maximum beam scanning speed in the irradiation nozzle 106, and specifically, the upper limit of the irradiation dose of the sub-regions can be determined based on the maximum beam intensity or maximum beam scanning speed previously stored in the treatment planning device 111.

[0088] Returning to FIG. 10, next, the treatment planning system 111 performs optimization of the layer and range modulator (step S1005).

[0089] First, the upper and lower limits of the number of layers are set.

[0090] As the number of layers increases, the irradiation time increases due to multiple energy change times, and it is thought that the FLASH effect will be reduced, so the irradiation time threshold of the FLASH effect is used as a guide for the upper number of layers. Therefore, the upper number of layers is calculated, for example, by dividing the irradiation time threshold at which the FLASH effect disappears by the energy change time. The lower number of layers is determined, for example, by taking into account the target size.

[0091] The upper and lower limit numbers of layers may be input by a doctor via the UI device 805 for each treatment, or values ​​previously stored in the storage device 803 may be automatically called up. In the subsequent optimization calculations, only the number of layers that is equal to or greater than the lower limit number of layers and equal to or less than the upper limit number of layers can be set as a condition.

[0092] Next, the treatment planning system 111 calls up from the storage device 803 a range modulation pattern having the same number as the degrees of freedom of the range modulator and corresponding beam data 810 .

[0093] Next, the treatment planning system 111 performs optimization calculations again to impart the target dose while taking into account the FLASH effect.

[0094] The optimization calculation is performed by finding irradiation parameters that minimize the objective function F'(x';N,p), which is a function of vector x' representing the amount of pencil beam irradiation at each irradiation position, as shown in the following equation (2), when, for example, Nn is the number of layers used to irradiate the nth sub-region, and N and p are vectors whose components are range modulator pattern pn, which is a term for the type of range modulator 306, 601 and blade 704.

[0095]

number

[0096] In formula (2), dlF(x';N,p) represents the effective dose given to the calculation point l when the FLASH effect is taken into account. Also, x' is a vector in which the components of the vector x representing the dose are rearranged so as to include the irradiation order information determined by the subregion division program 808. The reason why x' is more appropriate than x as the argument of dlF is as follows.

[0097] One calculation model for the effective dose taking into account the FLASH effect is to assume a threshold dose rate for manifesting the FLASH effect, and when the dose rate at the calculation point exceeds the threshold dose rate, the effective dose is calculated by multiplying the dose by a coefficient f (≦1).

[0098] The dose rate calculated here is a quantity determined by the time progression of the dose applied to each small area in the patient's body, and generally depends on the beam intensity, energy, irradiation position, scanning path and speed, etc., but there are various possible definitions.

[0099] For example, there are the average dose rate obtained by dividing the dose by the total time required for irradiation, the dose average dose rate defined as the dose rate weighted and averaged by the magnitude of the dose, and the pencil beam scanning dose rate defined by dividing a portion of the dose given to each micro area by the irradiation time. In particular, the pencil beam scanning dose rate clearly changes its value depending on the order of irradiation to each irradiation position, so it is necessary to use a vector x' containing irradiation order information as an argument.

[0100] The calculation model for the effective dose is not limited to the above, and for example, a coefficient f (≦1) that varies according to a FLASH dose ratio that represents the proportion of the total dose irradiated that satisfies a preset threshold dose rate may be used, or no threshold value may be set for the dose rate, etc., and the coefficient f may be a quantity that changes continuously depending on the dose, dose rate, or irradiation time.

[0101] In addition, the parameters x', N, and p do not need to be determined simultaneously by optimization, and some parameters may be determined first, and then the remaining parameters may be optimized. For example, the number of layers N may be determined first within the range of the lower limit number of layers and the upper limit number of layers, and then the dose and range modulator pattern may be optimized simultaneously, or the number of layers, range modulator, and dose may be determined in that order.

[0102] Furthermore, any initial value may be used to optimize the dose, but by setting the initial value based on the optimization vector x obtained in the dose optimization calculation, it is expected that the optimization calculation time will be shortened.

[0103] For example, consider the case of optimizing the dose after determining the number of layers and the range modulator pattern using Fig. 12. Fig. 12 focuses on a group of spots with the same XY coordinates when the target 209 is viewed from the YZ plane, and illustrates at the bottom the dose distribution formed by the beam irradiated to the group of spots.

[0104] Before the layer range modulator is optimized, the irradiation of the target spot group is formed by multiple pencil beams 1202A, 1202B, 1202C, and 1202D, whereas after the layer range modulator is optimized, the irradiation is formed by a single SOBP 1201. Therefore, after the layer range modulator is optimized, the total number of pencil beams generally decreases, but the irradiation amount of each pencil beam increases to include the irradiation amount of the multiple pencil beams before optimization.

[0105] The dose x'i of an arbitrary beam after optimization of the layer range modulator is estimated as x'i~Σjxj from the doses xj (j=1,…,m) of the pencil beams contained in this beam before optimization. Strictly speaking, optimization must be performed using the objective function F' in equation (2), but the calculation can be speeded up by using the above estimated value as the initial value.

[0106] In equation (2), optimization is performed simultaneously for all calculation points l within the patient's body. However, when it is approximated that the pencil beam irradiated to the n-th subregion does not contribute to the effective dose distribution of other subregions, that is, when calculation point l belongs to the n-th subregion and the vector whose components are the irradiation doses of each beam irradiated to the n-th subregion is xn, ..., it is approximated that dlF(x';N,p) ≒ dlF(xn, ...;Nn,pn), optimization may be performed for each subregion using an independent objective function Gn' for each subregion, as exemplified in the following equation (3).

[0107] In this way, the number of layers, the type of range modulators 306, 601 and wing 704, and the objective functions used to determine the irradiation position and dose of the particle beam can be given independently for each of the sub-regions 1102A and 1102B.

[0108]

number

[0109] Here, in equation (3), target(n) and OAR(n) represent the regions of the target and organ at risk within the nth subregion.

[0110] By performing optimization for each subregion independently, calculations may be faster than optimizing all regions simultaneously, depending on the target shape and target dose. On the other hand, if the approximation that other subregions do not contribute to the effective dose distribution is not sufficiently valid, the difference between the delivered dose and the target dose may become large in regions where the dose contributions of different subregions are mixed, so caution is required when adopting this method.

[0111] Returning to the layer and range modulator optimization procedure shown in Fig. 10, the treatment planning system 111 then creates a prescription reflecting the optimization calculation results. The prescription specifies irradiation parameters such as the energy of each pencil beam, the irradiation position, the irradiation amount, the irradiation direction, the irradiation sequence, and the range modulator pattern.

[0112] The effective dose distribution formed by the prescription is confirmed by the doctor via the UI device 805 (step S1006), and once the doctor has approved, the prescription is transmitted to the overall control device 108.

[0113] The overall controller 108 creates control instruction data based on the received prescription and transmits it to the accelerator / beam controller 109 and the irradiation controller 110. The transmitted data is stored in memory in the accelerator / beam controller 109 and the irradiation controller 110. This completes the creation of the prescription. If approval is not given, the process returns to step S1002, and the target dose or irradiation direction is reset.

[0114] Returning to FIG. 9, next, the patient is placed on the treatment table 107 and positioned to coincide with the time of capturing the in-vivo image, and then the particle beam therapy system 101 starts irradiating the beam 103 (step S903).

[0115] Irradiation is performed in order for each sub-region divided in step S902. A detailed procedure from preparation for irradiation of the first sub-region (step S904) to completion of irradiation (step S906) will be described with reference to FIG.

[0116] As shown in FIG. 13, first, the range modulation system 204 changes the arrangement of the range modulator according to the range modulator pattern information of the prescription (step S1301).

[0117] Next, among the layers included in the irradiation of the first sub-region, preparation for irradiation of the first layer is performed (step S1302). The accelerator system / beam transport system control device 109 changes parameters of the accelerator system 104, the beam transport system 105, and the irradiation nozzle 106, or some of them, to irradiate a beam with energy corresponding to the first layer (step S1303).

[0118] For example, if the accelerator system 104 includes a synchrotron, which is a variable-energy accelerator, the energy of the beam emitted is changed according to the parameters of the accelerator system 104, and the parameters of the beam transport system 105 are also adjusted to transport the beam of that energy to the irradiation nozzle 106.

[0119] On the other hand, when the accelerator system 104 is composed of a cyclotron that emits a beam of constant energy, the beam energy is changed after extraction by changing the thickness of the range shifter 205 installed in the beam transport system 105 or the irradiation nozzle 106.

[0120] Next, among the spots included in the first sub-region and the first layer, preparation for irradiation of the first spot is performed (step S1304). Specifically, the accelerator system / beam transport system control device 109 starts accelerating a beam with energy corresponding to the first layer.

[0121] Moreover, the irradiation controller 110 changes the current values ​​of the scanning magnets 201A and 201B via the scanning magnet controller 208 based on the irradiation position information of the prescription (step S1305).

[0122] When the irradiation preparations in steps S1301 to S1305 are completed, the accelerator system / beam transport system controller 109 starts beam extraction (step S1306). The extracted beam 103 passes through the irradiation nozzle 106 and is irradiated to the target 209. The characteristics of the irradiated beam 103 are monitored by the dose monitor 202 and the position monitor 203, and the irradiation dose is integrated in the irradiation controller 110. When the irradiation dose reaches the target dose, the irradiation controller 110 transmits a completion signal to the overall controller 108. The overall controller 108, which has received the completion signal, issues instructions to the accelerator system / beam transport system controller 109 and the irradiation controller 110, instructing them to prepare for irradiation of the second spot and to change the beam acceleration and scanning magnet current values.

[0123] When steps S1304 and S1305 are repeated for all spots included in the first sub-region and the first layer (Yes in step S1307), irradiation of the first layer is completed (step S1308).

[0124] Next, the beam energy is changed to that corresponding to the second layer, and irradiation is repeated for all spots included in the first sub-region and the second layer. Steps S1302 to S1307 are repeated for all layers included in the first sub-region (Yes in step S1309), and irradiation of the first sub-region is completed (step S906).

[0125] In this way, switching of the range modulators 306, 601 and vanes 704 can be performed during switching between sub-areas 1102A, 1102B.

[0126] 9, the above procedure is repeated for all sub-regions divided in the treatment plan, and the treatment for the day is completed (Yes in step S907). The same procedure is performed until the final treatment day (Yes in step S908), and the particle beam therapy in this embodiment is completed. The treatment procedure by the particle beam therapy system 101 is completed.

[0127] 13 is an example, and the timing of changing each parameter may be simultaneous or may be different. For example, the beam acceleration may be started in parallel with changing the arrangement of the range modulator.

[0128] Next, the effects of this embodiment will be described.

[0129] To maximize the beam utilization efficiency, it is desirable to change the energy by the accelerator within the range allowed for the FLASH effect, and to adjust the width of the SOBP to form a uniform dose distribution in the tumor with this small number of energies. In other words, by minimizing the energy loss in the range modulator, the radioactivity of the device can also be suppressed.

[0130] Therefore, the particle beam therapy system 101 of the above-mentioned embodiment 1 of the present invention includes an accelerator system 104 and an irradiation nozzle 106 for irradiating the target 209 with particle beams of multiple energies, a range modulator 306, 601 and a wing 704 for expanding the width of the Bragg peak of the particle beam, and a treatment planning device 111 for dividing the target 209 into multiple sub-regions 1102A, 1102B and determining the number of layers for dividing the target 209 in the traveling direction of the particle beam, the energy of the particle beam for each layer, the type of the range modulator 306, 601 and the wing 704, and the irradiation position and irradiation amount of the particle beam for each sub-region 1102A, 1102B so as to achieve a target dose set for the target 209.

[0131] In this way, by optimizing the number of layers, range modulator pattern, and irradiation dose per spot so that the effective dose taking into account the FLASH effect imparted to the target and risk organs satisfies the target value as much as possible, and performing particle beam therapy based on the optimization results, it is possible to simultaneously achieve dose concentration around the target and the FLASH effect in risk organs.

[0132] In the particle beam therapy system 101 of the first embodiment, the target 209 is divided into a plurality of sub-regions in the lateral plane, thereby suppressing a decrease in the dose rate due to particle reacceleration in the synchrotron during irradiation of a single sub-region or the need for long-distance beam scanning. The above process makes it easier for the FLASH effect to be produced in each sub-region, and enables FLASH therapy in many parts of the target even if the target has a large volume.

[0133] Furthermore, in the particle beam therapy system 101 of the first embodiment, since a dose distribution in the beam traveling direction is formed using a plurality of layers, the width of the SOBP expanded by the range modulator may be smaller than the thickness of the target 209. In other words, since there is no need to significantly attenuate the energy of the beam by a thick range modulator, the beam utilization efficiency is high, and the influence of activation due to the absorption and scattering of the beam by the range modulator can be suppressed.

[0134] In addition, the range modulation system 204, 204A and the range modulation wheel 701 are equipped with range modulators 306, 601 and wings 704 of different shapes, and modulator fixing mechanisms 305, 602A, 602B, 602C that can move the range modulators 306, 601 and wings 704 onto the trajectory of the particle beam when irradiating the target 209 with particle beams of multiple energies. This makes it possible to use a range modulator optimized to satisfy the irradiation time constraints resulting from the FLASH effect, thereby efficiently utilizing the beam to improve the FLASH effect in scanning particle beam therapy, while suppressing a decrease in dose concentration, and improving the biological effect in particle beam therapy.

[0135] Furthermore, the treatment planning system 111 can execute optimization calculations taking into account the FLASH effect by executing optimization calculations using an objective function having terms for the number of layers, the range modulators 306 and 601, and the type of the wing 704.

[0136] In addition, since the objective functions used to determine the number of layers, the type of range modulators 306, 601, and wing 704, and the particle beam irradiation position and dose are given independently for each sub-region 1102A, 1102B, it is expected that calculations can be performed faster than optimizing all regions simultaneously, depending on the target shape and target dose.

[0137] Furthermore, the treatment planning device 111 first determines the particle beam irradiation position and irradiation dose, and then divides the sub-regions 1102A, 1102B based on the irradiation dose, thereby avoiding problems such as uneven irradiation doses for each of the sub-regions 1102A, 1102B, and achieving more accurate particle beam irradiation.

[0138] Furthermore, the treatment planning device 111 divides the sub-regions 1102A, 1102B based on the number of accelerated particles in the synchrotron that constitutes the accelerator system 104 and the irradiation nozzle 106, thereby reliably preventing particle re-acceleration in the synchrotron during irradiation of a single sub-region, thereby further improving the FLASH effect while suppressing a decrease in dose concentration.

[0139] Furthermore, the treatment planning device 111 divides the sub-regions 1102A, 1102B based on the maximum beam intensity in the cyclotron that constitutes the accelerator system 104 or the maximum beam scanning speed in the irradiation nozzle 106.Since the sub-regions are divided based on the irradiation time, which is a constraint in the cyclotron that is capable of quasi-continuous beam emission, it is possible to reliably avoid the occurrence of particle re-acceleration during irradiation of a single sub-region, thereby further improving the FLASH effect while suppressing a decrease in dose concentration.

[0140] Furthermore, since the upper limit of the number of layers is determined in advance based on the biological effect, irradiation that maximizes the effect of particle beam irradiation can be achieved.

[0141] Furthermore, the range modulators 306, 601 and the vanes 704 are switched between the sub-areas 1102A, 1102B. The range modulator pattern is changed by mechanical control and its operation, and therefore takes a change time of several milliseconds to several seconds. Therefore, by making the change only when the irradiated sub-area transitions, the change can be made at the same time as the beam energy change and particle re-acceleration, which also take a longer time than the irradiation time, and therefore it is possible to make the change without significantly affecting the manifestation of the FLASH effect in the sub-area.

[0142] Furthermore, the range modulators 306, 601 and wings 704 are arranged in at least two types of multiple range modulators 306, 601 and wings 704 with different shapes, arranged in a direction perpendicular to the direction of travel of the particle beam, and are capable of moving at least in the perpendicular direction. The range modulator 601 is arranged in at least two types of multiple range modulators 601 with different shapes, arranged in the direction of travel of the particle beam, and are capable of moving at least in the direction perpendicular to the direction of travel. This further increases the degree of freedom of the SOBP width, and enables irradiation of the particle beam in a manner that is more in line with the shape of the affected area.

[0143] <Example 2> Second Embodiment A particle beam therapy system, a treatment planning device and a range modulator system according to a second embodiment of the present invention will be described with reference to FIG.

[0144] The overall configuration of the particle beam therapy system of this embodiment shown in Fig. 14 is similar to that of the first embodiment, but there is a difference in a part of the treatment planning flow as shown in Fig. 14. Specifically, the treatment planning device 111 divides the sub-regions 1102A and 1102B based on the target dose.

[0145] The steps from the start of particle beam therapy on each treatment day (step S901) to the input of the target dose and irradiation direction in the treatment plan (step S1402) are the same as those in embodiment 1. Next, in embodiment 2, sub-region division and layer / range modulator optimization are performed before performing dose optimization.

[0146] First, the treatment planning system 111 calls the subregion division program 808, and divides the target 209 into a plurality of subregions within the XY plane (step S1403).

[0147] In the first embodiment, the upper dose limit is calculated from equipment constraints such as the number of accelerated particles, and the subregion is divided so that the sum of the doses represented by the vector x within the subregion does not exceed the upper dose limit. However, in the second embodiment, the division is performed before the dose vector x is calculated by dose optimization, so that division based on the vector x cannot be performed. Instead, the treatment planning device 111 estimates the dose of each pencil beam from the target dose input by the doctor, and uses this to determine the division of the subregion.

[0148] After the sub-region division is completed, the treatment planning device 111 performs optimization of the dose, layer, and range modulator (step S1404). The optimization procedure is similar to the layer / range modulator optimization (step S1005) in the first embodiment, and optimizes the number of layers, range modulation pattern, and dose based on the dose distribution taking into account the FLASH effect using equation (2) and the like. Any value may be used as the initial value of the dose in the optimization, and for example, the dose estimated from the above-mentioned target dose may be used.

[0149] After the dose layer and range modulator pattern optimization is completed, the executed dose distribution is displayed on the UI device 805, and the doctor is prompted to decide whether or not to approve it, as in the first embodiment. The subsequent particle beam therapy flow is the same as in the first embodiment.

[0150] The other configurations and operations are substantially the same as those of the particle beam therapy system, treatment planning device, and range modulator system of the first embodiment described above, and the details are omitted here.

[0151] In the particle beam therapy system, treatment planning device, and range modulator system of the second embodiment of the present invention, the dose optimization performed first in the treatment plan of the first embodiment is omitted, and layer range modulator optimization and dose optimization are performed after the sub-region division. Therefore, since the number of optimizations is smaller than that of the first embodiment, the treatment planning time may be shortened depending on the conditions such as the target shape and the target dose. On the other hand, since the sub-region division is performed using the estimated dose based on the target dose, the result of the division of the sub-region does not necessarily maximize the FLASH effect. Therefore, it is desirable to apply this embodiment appropriately according to the conditions such as the target shape and the target dose.

[0152] As described above, the second embodiment is the same as the first embodiment except for a part of the treatment planning flow. Therefore, the same effects as those described in the first embodiment are expected, and the dose concentration around the target and the FLASH effect in dangerous organs can be simultaneously achieved in particle beam therapy, and FLASH treatment can be performed on many parts of the target even in cases where the target is large. In addition, the beam utilization efficiency is improved, and the effect of activation is suppressed.

[0153] Furthermore, the treatment planning system 111 can reduce the treatment planning time by dividing the sub-regions 1102A and 1102B based on the target dose.

[0154] <Other> The present invention is not limited to the above-mentioned embodiment, but includes various modified examples. The above-mentioned embodiment has been described in detail to explain the present invention in an easily understandable manner, and the present invention is not necessarily limited to the embodiment having all of the described configurations.

[0155] It is also possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace part of the configuration of each embodiment with the configuration of another embodiment.

[0156] For example, the objective function of the irradiation optimization calculation is not limited to the formula shown in formula (1) etc., and each term in formula (1) may have a different functional form, or new terms may be added according to clinical requirements or equipment constraints. In addition, optimization may be performed so that the histograms of the volume irradiated above a certain dose or dose rate (dose-volume histogram and dose-rate-volume histogram, respectively) have the target properties, or robust optimization may be performed that takes into account the effects of errors in the patient position and beam arrival position on the dose distribution and dose rate distribution.

[0157] Furthermore, in the above embodiment, irradiation of the beam at different irradiation positions is realized by a scanning method using a scanning magnet, but it may be realized by a passive method using a variable collimator.

[0158] The embodiment of the present invention may be in the following form.

[0159] (1) A particle beam therapy system comprising: an irradiation system for irradiating an irradiation target with particle beams of multiple energies; multiple range modulators for expanding a width of the Bragg peak of the particle beam; and a planning device for dividing the irradiation target into multiple sub-regions and determining, for each of the sub-regions, the number of layers into which the irradiation target is divided in a traveling direction of the particle beam so as to achieve a target dose set for the irradiation target, the energy of the particle beam for each of the layers, the type of the range modulator, and the irradiation position and irradiation dose of the particle beam.

[0160] (2) In the particle beam therapy system described in (1), the planning device performs optimization calculations using an objective function having terms for the number of layers and the type of range modulator.

[0161] (3) In the particle beam therapy system described in (2), the number of layers, the type of the range modulator, and an objective function used to determine the irradiation position and irradiation dose of the particle beam are given independently for each of the sub-regions.

[0162] (4) In the particle beam therapy system according to any one of (1) to (3), the planning device first determines an irradiation position and an irradiation dose of the particle beam, and then divides the sub-region based on the irradiation dose.

[0163] (5) In the particle beam therapy system according to any one of (1) to (3), the planning device divides the sub-regions based on the target dose.

[0164] (6) In the particle beam therapy system according to any one of (1) to (3), the planning device divides the sub-regions based on the number of accelerated particles in a synchrotron constituting the irradiation system.

[0165] (7) In a particle beam therapy system according to any one of (1) to (3), the planning device divides the sub-regions based on a maximum beam intensity in a cyclotron constituting the irradiation system or a maximum beam scanning speed in the irradiation system.

[0166] (8) In the particle beam therapy system according to any one of (1) to (7), an upper limit on the number of layers is determined in advance based on a biological effect.

[0167] (9) In the particle beam therapy system according to any one of (1) to (8), the range modulator is switched during the switching of the sub-areas.

[0168] (10) In a particle beam therapy system described in any one of (1) to (9), the range modulator has at least two or more types of range modulators of different shapes arranged in a direction perpendicular to the direction of propagation of the particle beam, and is capable of moving at least in the perpendicular direction.

[0169] (11) In a particle beam therapy system described in any one of (1) to (9), the range modulator has at least two or more types of range modulators of different shapes arranged in the direction of propagation of the particle beam, and is capable of moving at least in a direction perpendicular to the direction of propagation.

[0170] (12) A treatment planning device that creates a treatment plan for irradiating an irradiation target with particle beams of multiple energies, the treatment planning device dividing the irradiation target into multiple sub-regions, and determining, for each sub-region, the number of layers into which the irradiation target is divided in the traveling direction of the particle beam so as to achieve a target dose set for the irradiation target, the energy of the particle beam for each layer, the types of multiple range modulators that expand the width of the Bragg peak of the particle beam, and the irradiation position and irradiation dose of the particle beam.

[0171] (13) In the treatment planning system according to (12), an optimization calculation is performed using an objective function having terms for the number of layers and the type of range modulator.

[0172] (14) In the treatment planning system described in (13), the number of layers, the type of the range modulator, and an objective function used to determine the irradiation position and irradiation dose of the particle beam are given independently for each of the sub-regions.

[0173] (15) In the treatment planning system according to any one of (12) to (14), first, the irradiation position and the irradiation amount of the particle beam are determined, and then the division of the sub-region is performed based on the irradiation amount.

[0174] (16) In the treatment planning system according to any one of (12) to (14), the division of the sub-regions is performed based on the target dose.

[0175] (17) In the treatment planning system according to any one of (12) to (14), the division of the sub-regions is performed based on the number of particles accelerated in a synchrotron constituting an irradiation system.

[0176] (18) In the treatment planning system according to any one of (12) to (14), the division of the subregions is performed based on a maximum beam intensity in a cyclotron constituting an irradiation system or a maximum beam scanning speed in the irradiation system.

[0177] (19) In the treatment planning system according to any one of (12) to (18), an upper limit on the number of layers is determined in advance based on a biological effect.

[0178] (20) In the treatment planning system according to any one of (12) to (19), the range modulator is switched between the sub-regions. [Explanation of symbols]

[0179] 101: Particle Therapy System 102:Patient 103: Beam 104: Accelerator system (irradiation system) 105: Beam transport system 106: Irradiation nozzle (irradiation system) 107: Treatment table 108: Overall control device 109: Accelerator and beam transport system control device 110: Irradiation control device 111: Treatment planning device (planning device) 112:Injector 113: Synchrotron accelerator 114: Ion source 115: Bending electromagnet 201A, 201B: Scanning electromagnet 202: Dose monitor 203: Position monitor 204, 204A: Range modulation system 205: Range shifter 206...Dose monitor signal processing system 207... Position monitor signal processing system 208: Scanning magnet control device 209: Target (irradiation target) 301:X-axis 302: Y axis 303:Z-axis 304: Modulation System Wall 305: Modulator fixing mechanism (moving mechanism) 306: Range Modulator 401: Unit Structure 402: Ridge width 403: Ridge thickness 501, 501A, 501B, 501C, 501D: Modulator elements 601, 601A, 601B, 601C: Range Modulator 602A, 602B, 602C: Modulator fixing mechanism (moving mechanism) 701: Range Modulation Wheel (Range Modulation System) 702: Exterior wall 703: Rotation axis 704: Feather (Range Modulator) 801:CPU 802:Memory 803: Storage device 804: Communication interface 805:UI device 806:OS 807: Dose optimization program 808: Sub-domain division program 809:Layer Range Modulator Optimization Program 810:Beam data 1101: Spot 1102A, 1102B: Sub-area 1103: Irradiation order 1201:SOBP 1202A, 1202B, 1202C, 1202D: Pencil beam

Claims

1. an irradiation system for irradiating an irradiation target with particle beams of multiple energies; a plurality of range modulators for expanding the width of the Bragg peak of the particle beam; and a planning device that divides the irradiation target into a plurality of sub-regions, and determines, for each sub-region, the number of layers into which the irradiation target is divided in the traveling direction of the particle beam, the energy of the particle beam for each layer, the type of the range modulator, and the irradiation position and irradiation amount of the particle beam so as to achieve a target dose set for the irradiation target. Particle beam therapy system.

2. 2. The particle beam therapy system according to claim 1, The planning device executes an optimization calculation using an objective function having terms of the number of layers and the type of range modulator. Particle beam therapy system.

3. 3. The particle beam therapy system according to claim 2, The number of layers, the type of the range modulator, and an objective function used to determine the irradiation position and the irradiation amount of the particle beam are given independently for each of the sub-regions. Particle beam therapy system.

4. 2. The particle beam therapy system according to claim 1, The planning device first determines the irradiation position and the irradiation dose of the particle beam, and then divides the sub-region based on the irradiation dose. Particle beam therapy system.

5. 2. The particle beam therapy system according to claim 1, The planning device performs the division of the sub-regions based on the target dose. Particle beam therapy system.

6. 2. The particle beam therapy system according to claim 1, The planning device divides the sub-areas based on the number of accelerated particles of a synchrotron constituting the irradiation system. Particle beam therapy system.

7. 2. The particle beam therapy system according to claim 1, The planning device divides the sub-regions based on a maximum beam intensity in a cyclotron constituting the irradiation system or a maximum beam scanning speed in the irradiation system. Particle beam therapy system.

8. 2. The particle beam therapy system according to claim 1, The upper limit of the number of layers is predetermined based on a biological effect. Particle beam therapy system.

9. 2. The particle beam therapy system according to claim 1, The range modulator switching is performed during the sub-region switching. Particle beam therapy system.

10. 2. The particle beam therapy system according to claim 1, The range modulator has at least two or more types of range modulators having different shapes arranged in a direction perpendicular to the traveling direction of the particle beam, and is movable at least in the perpendicular direction. Particle beam therapy system.

11. 2. The particle beam therapy system according to claim 1, The range modulator has at least two or more types of range modulators having different shapes arranged in the traveling direction of the particle beam, and is movable at least in a direction perpendicular to the traveling direction. Particle beam therapy system.

12. A treatment planning apparatus for creating a treatment plan for irradiating an irradiation target with particle beams of multiple energies, comprising: The irradiation target is divided into a plurality of sub-regions, and the number of layers into which the irradiation target is divided in the traveling direction of the particle beam, the energy of the particle beam for each of the layers, the types of a plurality of range modulators that expand the width of the Bragg peak of the particle beam, and the irradiation position and irradiation amount of the particle beam are determined for each of the sub-regions so as to achieve a target dose set for the irradiation target. Treatment planning device.

13. 13. The treatment planning system of claim 12, Execute an optimization calculation using an objective function having terms for the number of layers and the type of range modulator. Treatment planning device.

14. 14. The treatment planning system of claim 13, The number of layers, the type of the range modulator, and an objective function used to determine the irradiation position and the irradiation amount of the particle beam are given independently for each of the sub-regions. Treatment planning device.

15. 13. The treatment planning system of claim 12, First, the irradiation position and the dose of the particle beam are determined, and then the sub-region is divided based on the dose. Treatment planning device.

16. 13. The treatment planning system of claim 12, performing segmentation of the sub-regions based on the target dose Treatment planning device.

17. 13. The treatment planning system of claim 12, The sub-regions are divided based on the number of particles accelerated by a synchrotron constituting the irradiation system. Treatment planning device.

18. 13. The treatment planning system of claim 12, The division of the sub-regions is performed based on a maximum beam intensity in a cyclotron constituting the irradiation system or a maximum beam scanning speed in the irradiation system. Treatment planning device.

19. 13. The treatment planning system of claim 12, The upper limit of the number of layers is predetermined based on a biological effect. Treatment planning device.

20. 13. The treatment planning system of claim 12, The range modulator switching is performed during the sub-region switching. Treatment planning device.

21. A plurality of range modulators of different shapes; The range modulator is provided with a moving mechanism capable of moving the range modulator onto the trajectory of the particle beam when irradiating the particle beam with multiple energies to the irradiation target. Range Modulator System.

22. 22. The range modulator system of claim 21, At least two types of range modulators are arranged in a direction perpendicular to the traveling direction of the particle beam, The moving mechanism moves the object in at least the vertical direction. Range Modulator System.

23. 22. The range modulator system of claim 21, At least two types of range modulators are arranged in the traveling direction of the particle beam, The moving mechanism moves the object in at least a direction perpendicular to the traveling direction. Range Modulator System.

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