JP2018143659A - Charged particle beam treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charged particle beam treatment device which can efficiently irradiate the charged particle beam according to a shape of the subject to be irradiated.SOLUTION: A charged particle beam treatment device 1 includes an enlargement amount adjusting part 102 for adjusting an enlargement amount of a charged particle beam R by an enlargement part 70 according to a shape of a tumor 14. With this configuration, when the tumor 14 becomes smaller as shown in Fig. 6(b), for example, the enlargement amount adjusting part 102 can also decrease the enlargement amount of the charged particle beam R accordingly. Therefore, among the charged particle beam R, the beam shielded by the multi-leaf collimator 24 can be decreased. Also, by decreasing the enlargement amount of the charged particle beam R according to an irradiation field of the multi-leaf collimator 24, an occurrence of a half shadow can also be suppressed.SELECTED DRAWING: Figure 6

Description

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

  Conventionally, for example, an apparatus described in Patent Document 1 is known as a charged particle beam therapy apparatus that performs treatment by irradiating a patient's affected part with a charged particle beam. In the charged particle beam treatment apparatus described in Patent Document 1, the charged particle beam accelerated by the accelerator is enlarged, and some unnecessary charged particle beams are blocked using a collimator, and then matched to the shape of the irradiated object. The charged particle beam is irradiated in the irradiated field.

JP 2009-236867 A

  Here, in the charged particle beam therapy system as described above, the charged particle beam that is blocked by the collimator is not used for irradiating the irradiated object, so that there is a problem that the dose is wasted. In addition, when the collimator irradiation field is small compared to the amount of enlargement of the charged particle beam, the penumbra may become large due to the distribution of the phase space of the particles.

  Then, an object of this invention is to provide the charged particle beam therapeutic apparatus which can irradiate a charged particle beam efficiently according to the shape of a to-be-irradiated body.

  In order to solve the above problems, a charged particle beam treatment apparatus according to the present invention includes an accelerator that accelerates charged particles and emits the charged particle beam, an irradiation unit that irradiates the irradiated object with the charged particle beam, and irradiation. An enlarged portion for enlarging the charged particle beam, a collimator for defining the irradiation range of the charged particle beam according to the shape of the irradiated object, and a charged particle beam by the expanding portion according to the shape of the irradiated object. An enlargement amount adjustment unit for adjusting the enlargement amount.

  A charged particle beam treatment apparatus according to the present invention includes an enlargement unit that is provided in an irradiation unit and expands the charged particle beam, and a collimator that defines an irradiation range of the charged particle beam according to the shape of the irradiated object. Yes. Therefore, the vicinity of the outer edge of the charged particle beam magnified by the magnifier is shielded by the collimator, and the portion that has passed through the collimator is irradiated to the irradiated object. Here, the charged particle beam therapy system includes an enlargement amount adjustment unit that adjusts the enlargement amount of the charged particle beam by the enlargement unit in accordance with the shape of the irradiated object. Thereby, for example, when the irradiated body becomes small, the enlargement amount adjustment unit can reduce the enlargement amount of the charged particle beam accordingly. Therefore, the dose shielded by the collimator among the charged particle beams can be reduced. Moreover, the occurrence of penumbra can be suppressed by reducing the enlargement amount of the charged particle beam in accordance with the irradiation field of the collimator. As mentioned above, according to the shape of a to-be-irradiated body, a charged particle beam can be irradiated efficiently.

  In the charged particle beam therapy system, the enlargement unit includes a plurality of scatterers that diffuse the charged particle beam, and the enlargement amount adjustment unit adjusts the amount of enlargement of the charged particle beam by adjusting the number of scatterers. It's okay. Thereby, an enlarged amount adjustment part can expand a charged particle beam appropriately by adjusting the number of scatterers according to the shape of a to-be-irradiated body.

  In the charged particle beam therapy system, the enlargement amount adjustment unit may adjust the enlargement amount of the charged particle beam irradiated to each layer when the irradiated object is virtually divided into a plurality of layers in the depth direction. . Thereby, according to the shape of each layer of a to-be-irradiated body, a charged particle beam can be irradiated efficiently.

  ADVANTAGE OF THE INVENTION According to this invention, the charged particle beam therapeutic apparatus which can irradiate a charged particle beam efficiently according to the shape of a to-be-irradiated body can be provided.

1 is a schematic configuration diagram of a charged particle beam therapy system according to an embodiment of the present invention. It is a schematic block diagram of the irradiation part vicinity of the charged particle beam therapy apparatus of FIG. It is the figure which looked at the multileaf collimator from the irradiation axis direction. It is a schematic diagram for demonstrating the expansion amount of a charged particle beam. It is a flowchart which shows an example of the processing content by a charged particle beam therapy apparatus. It is a schematic diagram which shows the expansion of the charged particle beam of the charged particle beam therapy apparatus which concerns on this embodiment and a comparative example, and the relationship of a collimator. It is a schematic diagram which shows a mode that the to-be-irradiated body was divided | segmented into the virtual layer. It is a flowchart which shows an example of the processing content by the charged particle beam therapy apparatus which concerns on a modification.

  Hereinafter, a charged particle beam therapy system according to an embodiment of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 1, a charged particle beam therapy apparatus 1 according to an embodiment of the present invention is an apparatus used for cancer treatment or the like by radiation therapy, and charged particles generated by an ion source (not shown). Accelerating the beam 2 and emitting it as a charged particle beam, an irradiation unit 8 for irradiating the irradiated body with the charged particle beam, and a beam transport line 45 for transporting the charged particle beam emitted from the accelerator 2 to the irradiation unit 8 It is equipped with. The irradiation unit 8 is attached to a rotating gantry 17 provided so as to surround the treatment table 16. The irradiation unit 8 can be rotated around the treatment table 16 by a rotating gantry 17.

  In the following description, the terms “X direction”, “Y direction”, and “Z direction” will be used. The “Z direction” is a direction in which the base axis AX of the charged particle beam R extends. The “base axis AX” is an irradiation axis of the charged particle beam R when it is not deflected by scanning electromagnets 3a and 3b described later. FIG. 2 shows a state where the charged particle beam R is irradiated along the base axis AX. In the following description, the direction in which the charged particle beam R is irradiated along the base axis AX is assumed to be the “irradiation axis direction of the charged particle beam R”. The “X direction” is one direction in a plane orthogonal to the Z direction. The “Y direction” is a direction orthogonal to the X direction in a plane orthogonal to the Z direction.

  With reference to FIG. 2, the structure of the charged particle beam therapy apparatus which concerns on a wobbler method is demonstrated. As shown in FIG. 2, the charged particle beam therapy system 1 includes an accelerator 2, scanning electromagnets 3a and 3b, monitors 4a and 4b, a scattering unit 5, a ridge filter 22, a multi-leaf collimator 24, a bolus 26, a patient collimator 27, and a degrader. 30, a control device 7, and a treatment planning device 100. Scanning electromagnets 3a and 3b, monitors 4a and 4b, scattering unit 5, ridge filter 22, multi-leaf collimator 24, bolus 26, patient collimator 27, and degrader 30 are arranged inside irradiation unit 8. The control device 7 is provided outside the irradiation unit 8.

  The accelerator 2 is a generation source that accelerates charged particles and continuously generates charged particle beams R. Examples of the accelerator 2 include a cyclotron, a synchrotron, a cyclosynchrotron, and a linac. The charged particle beam R generated by the accelerator 2 is transported to the irradiation unit 8 by a beam transport system. The accelerator 2 is connected to the control device 7, and the supplied current is controlled.

  The scanning electromagnets 3a and 3b are each composed of a pair of electromagnets, change the magnetic field between the pair of electromagnets according to the current supplied from the control device 7, and scan the charged particle beam R passing between the electromagnets. The X-direction scanning electromagnet 3a scans the charged particle beam R in the X direction (first scanning direction), and the Y-direction scanning electromagnet 3b in the Y direction (second scanning direction orthogonal to the first scanning direction). The charged particle beam R is scanned. These scanning electromagnets 3 a and 3 b are arranged in this order on the base axis AX and downstream of the accelerator 2.

  The monitor 4a monitors the beam position of the charged particle beam R, and the monitor 4b monitors the absolute value of the dose of the charged particle beam R and the dose distribution of the charged particle beam R. Each of the monitors 4a and 4b outputs the monitored monitoring information to the control device 7. The monitor 4a is disposed on the base axis AX of the charged particle beam R and downstream of the accelerator 2 and upstream of the X-direction scanning electromagnet 3a. The monitor 4b is disposed on the base axis AX and downstream of the Y-direction scanning electromagnet 3b.

  The scattering unit 5 diffuses the charged particle beam R passing therethrough into a wide beam having a spread in a direction orthogonal to the irradiation axis. The scatterer 5 according to the present embodiment includes a plurality of scatterers 5a and a drive unit 5b that drives the scatterers 5a. The drive unit 5b drives the scatterer 5a so that the scatterer 5a can advance and retreat with respect to the passing position of the charged particle beam R. The drive unit 5 b drives each scatterer 5 a based on a signal from the control device 7. Therefore, the control device 7 controls the drive unit 5b according to the set scattering angle of the charged particle beam R, and switches the number of scatterers 5a arranged at the passing position of the charged particle beam R. The scatterer 5a has a plate shape and is made of, for example, tungsten having a thickness of several millimeters. The scattering unit 5 is disposed on the upstream side of the monitor 4b on the downstream side of the scanning electromagnet 3b on the base axis AX.

  The ridge filter 22 adjusts the dose distribution of the charged particle beam R. Specifically, the ridge filter 22 gives an enlarged Bragg peak (SOBP) to the charged particle beam R so as to correspond to the thickness (length in the irradiation axis direction) of the tumor 14 in the body of the patient 13. The ridge filter 22 is disposed on the upstream side of the monitor 4b on the base axis AX and on the downstream side of the scattering unit 5.

  The degrader 30 adjusts the range of the charged particle beam R by reducing the energy of the charged particle beam R passing therethrough. The range is adjusted roughly by a degrader (not shown) provided immediately after the accelerator 2, and finely adjusted by the degrader 30 in the irradiation unit 8. The degrader 30 is provided on the base axis AX and on the downstream side of the charged particle beam R with respect to the scanning electromagnets 3a and 3b, and adjusts the maximum reachable depth of the charged particle beam R in the body of the patient 13. The degrader 30 is a plate-like member that extends in the X direction and the Y direction. In the present embodiment, the “range” is a distance traveled until the charged particle beam R loses kinetic energy and stops. More specifically, the range is a depth that is deeper than the irradiation distance (depth) at which the maximum dose is obtained and the dose is 90% when the maximum dose is 100%.

  The multi-leaf collimator 24 shapes the shape (planar shape) of the charged particle beam R in a plane direction perpendicular to the irradiation axis direction, and includes shielding portions 24a and 24b including a plurality of comb teeth. The shielding portions 24a and 24b are disposed so as to face each other, and an opening 24c is formed between the shielding portions 24a and 24b. The multi-leaf collimator 24 cuts the charged particle beam R into a contour corresponding to the shape of the opening 24c by passing the charged particle beam R through the opening 24c.

  Further, the multi-leaf collimator 24 can change the position and shape of the opening 24c by moving the shielding portions 24a and 24b back and forth in a direction orthogonal to the Z direction. Further, the multi-leaf collimator 24 is guided along the irradiation axis direction by the linear guide 28 and is movable along the Z direction. The multi-leaf collimator 24 is disposed on the downstream side of the monitor 4b.

  More specifically, as shown in FIG. 3, the multi-leaf collimator 24 has a pair of leaf groups 31 and 32 that face each other in the X direction. The pair of leaf groups 31 and 32 face each other in the X direction across the reference axis A on the XY plane orthogonal to the reference axis A. The pair of leaf groups 31 and 32 includes a leaf member 40 including a large number of leaves 41 that can be advanced and retracted independently in the X direction.

  The leaf member 40 includes a leaf 41 and a leaf driving unit 43 that moves the leaf 41. The leaf member 40 is disposed along the XY plane so that the leaf 41 of the leaf member 40 included in the leaf group 31 and the leaf 41 of the leaf member 40 included in the leaf group 32 face each other.

  The leaf 41 is a rectangular plate-like member extending along the X direction. Since the leaf 41 is a member used for shielding charged particle beams, the leaf 41 is manufactured from a material capable of shielding charged particle beams. Examples of the material capable of shielding charged particle beams include brass, copper, tantalum, and molybdenum, but it is preferable to use brass having a high shielding ability.

  The leaf drive unit 43 places each leaf 41 at the requested position based on the signal from the control device 7. The control device 7 sets the shape of the opening 24c of the multi-leaf collimator 24 according to the shape of the tumor 14 when viewed from the irradiation axis direction. The multi-leaf collimator 24 forms an opening 24 c so that the end of each leaf 41 is disposed at a position slightly away from the outer edge of the tumor 14.

  The bolus 26 shapes the three-dimensional shape of the portion where the charged particle beam R reaches the maximum depth to match the shape of the maximum depth portion of the tumor 14. The shape of the bolus 26 is calculated based on, for example, the outline of the tumor 14 and the electron density of the surrounding tissue obtained from the X-ray CT data. The bolus 26 is disposed on the downstream side of the multi-leaf collimator 24 on the base axis AX. The patient collimator 27 finally shapes the planar shape of the charged particle beam R in accordance with the planar shape of the tumor 14. The patient collimator 27 is disposed on the downstream side of the bolus 26 on the base axis AX. The bolus 26 and the patient collimator 27 are provided at the distal end 8 a of the irradiation unit 8.

  When the charged particle beam therapy apparatus 1 shown in FIG. 2 irradiates the charged particle beam R by the wobbler method, the degrader 30 that can be adjusted to a predetermined range is set, and the shielding portions 24a, 24a of the multi-leaf collimator 24 are set. 24b is advanced and retracted so that the opening 24c has a predetermined shape.

  Subsequently, a charged particle beam R is emitted from the accelerator 2. The emitted charged particle beam R is scanned in a circle by the scanning electromagnets 3a and 3b and diffused by the scattering unit 5, and then the ridge filter 22, the degrader 23, the multi-leaf collimator 24, the bolus 26, and the patient collimator 27. Is shaped and adjusted by Thereby, the charged particle beam R is irradiated to the tumor 14 in the uniform irradiation range along the shape of the tumor 14.

  For example, as shown in FIG. 4, the irradiation region E1 of the charged particle beam R with respect to a predetermined surface (for example, the upper surface of the multi-leaf collimator 24) includes the spot region S of the diffused charged particle beam R, and the spot region S It depends on the scanning range. That is, the irradiation area E1 is determined by scanning the spot area S having a predetermined size so as to draw a circle or draw a spiral. The size of the spot region S of the charged particle beam R is determined by the scattering angle θ2. The scattering angle θ2 is an angle of spread of the charged particle beam R with respect to the irradiation axis RX of the charged particle beam R. Further, in addition to the size of the spot area S, the irradiation area E1 is determined by the locus when the spot area S is drawing a circle on the outermost periphery side. The size of the circle on the outermost peripheral side of the spot region S is determined by the wobbler angle θ1. The wobbler angle θ1 is an angle of the irradiation axis RX of the charged particle beam R with respect to the base axis AX. The degree of spread of the charged particle beam R determined by the wobbler angle θ1 and the scattering angle θ2 is referred to as “enlargement amount”.

  The charged particle beam R is enlarged by moving the scanning range of the spot region S by the scanning electromagnets 3 a and 3 b and adjusting the size of the spot region S by the scattering unit 5. Therefore, in the following description, the scanning electromagnets 3a and 3b and the scattering unit 5 may be collectively referred to as “enlarged unit 70”. Thus, the enlargement unit 70 enlarges the irradiation region of the charged particle beam R by enlarging the spot region S itself and increasing the movement amount of the spot region S. The enlargement unit 70 enlarges the charged particle beam R so that the irradiation region covers at least the entire region of the opening 24c of the multi-leaf collimator 24. However, the enlargement unit 70 may enlarge the irradiation region of the charged particle beam R only by increasing the spot region S itself or increasing the movement amount of the spot region S. The trajectory for the movement of the spot region S is not limited to a circular or spiral trajectory, but may be a linear reciprocating trajectory.

  Next, a treatment plan of the charged particle beam treatment apparatus 1 that performs irradiation with the charged particle beam R in the above-described procedure will be described. The treatment plan of the charged particle beam treatment apparatus 1 is made by the treatment plan apparatus 100. As illustrated in FIG. 2, the treatment planning apparatus 100 includes at least an irradiation size determination unit 101 and an enlargement amount adjustment unit 102.

  The irradiation size determination unit 101 determines the irradiation size of the charged particle beam R according to the shape of the tumor 14. Here, the irradiation size is the size of the irradiation region at any position in the irradiation axis direction. Although any position (for example, isocenter) may be used as a reference, in the present embodiment, the determination of the irradiation size is described based on the size of the irradiation region E1 at the position of the upper surface of the multi-leaf collimator 24 as shown in FIG. It shall be. Note that the treatment planning apparatus 100 grasps the shape of the tumor 14 based on data such as CT acquired in advance. The treatment planning apparatus 100 can also plan the shape of the opening 24 c of the multi-leaf collimator 24 according to the shape of the tumor 14.

  Therefore, the irradiation size determination unit 101 determines the irradiation size of the charged particle beam R according to the shape of the tumor 14 when viewed from the irradiation axis direction and the shape of the opening 24c of the multi-leaf collimator 24. For example, when the shape of the opening 24c of the multi-leaf collimator 24 is set for the tumor 14 as shown in FIG. 3, the irradiation size determining unit 101 performs irradiation so that the irradiation region E1 includes the entire opening 24c. Determine the size. The irradiation size determination unit 101 grasps the size of the portion of the edge of the opening 24c farthest from the base axis AX, and sets the irradiation size so that the radius of the irradiation region E1 is larger than the size. decide. Further, the irradiation size determination unit 101 determines the irradiation size so that the irradiation region E1 does not become excessively large with respect to the opening 24c. For example, the irradiation size determination unit 101 calculates a Gaussian distribution (a lateral beam spread distribution by a pencil beam) on a XY plane when the base axis AX is a Z axis along the rotation path of a wobbler. The irradiation size may be calculated using the horizontal flatness formed by adding the distributions as an index. By swinging the wobbler angle from the smaller one to the larger one, it is possible to prevent the selection that the irradiation region E1 is too large.

  The enlargement amount adjustment unit 102 adjusts the enlargement amount of the charged particle beam R by the enlargement unit 70 according to the shape of the tumor 14. The enlargement amount adjustment unit 102 adjusts the enlargement amount based on the irradiation size so that the irradiation size determined by the irradiation size determination unit 101 is obtained. In this embodiment, the amount of enlargement of the charged particle beam R is determined by the scattering angle θ2 and the wobbler angle θ1. Therefore, the enlargement amount adjusting unit 102 adjusts the scattering angle θ2 and the wobbler angle θ1 to obtain a desired irradiation size. The scattering angle θ2 can be adjusted in a plurality of stages according to the number of scatterers 5a of the scattering portion 5. Therefore, the enlargement amount adjustment unit 102 selects the optimum scattering angle θ2 from those that can be selected by adjusting the scattering unit 5. Then, the enlargement adjustment unit 102 determines the wobbler angle θ1 in the X direction and the Y direction according to the selected scattering angle θ2.

  The treatment planning apparatus 100 determines the range of the charged particle beam R as well as the amount of enlargement of the charged particle beam R. In addition, the treatment planning apparatus 100 can calculate a dose distribution or the like when the treatment is performed under the condition based on the determined condition, and can readjust the various conditions.

  Next, with reference to FIG. 5, an example of the processing content by the charged particle beam therapy system 1 will be described. Note that the processing content of FIG. 5 is merely an example, and can be changed as appropriate.

  As shown in FIG. 5, the treatment planning apparatus 100 determines the irradiation size of the charged particle beam R (step S10). In S10, the treatment planning device 100 sets the shape of the opening 24c of the multi-leaf collimator 24 from the data of the tumor 14 acquired in advance. Then, the treatment planning apparatus 100 determines the irradiation size according to the shape of the tumor 14 when viewed from the irradiation axis direction, that is, the shape of the opening 24c. At this time, the treatment planning apparatus 100 determines the range of the charged particle beam R based on the depth of the tumor 14.

  The treatment planning apparatus 100 sets the enlargement amount of the charged particle beam R, that is, the wobbler angle θ1 and the scattering angle θ2 based on the irradiation size determined in S10 (step S20). When the wobbler angle θ1 and the scattering angle θ2 are set in S20, settings for various components in the apparatus are performed (step S30). For example, the treatment planning apparatus 100 sets the number of scatterers 5a (scatterer thickness) in the scatterer 5 to obtain the scattering angle θ2, or sets the degrader 30 according to the range.

  Next, the treatment planning apparatus 100 determines whether or not the flatness is within a specified value when it is assumed that the charged particle beam R is irradiated under various set conditions (step S40). In S40, for example, the lateral distribution of the dose of the charged particle beam R at the isocenter is calculated, and the flatness is calculated. At this time, the treatment planning apparatus 100 calculates the flatness by calculating the X- and Y-direction scattering radii at the isocenter based on the ridge filter 22 to be used.

  When it is determined in S40 that the flatness does not fall within the specified value, the treatment planning apparatus 100 adjusts the amount of enlargement of the charged particle beam R again (step S50). For example, the treatment planning apparatus 100 adjusts the wobbler angle θ1 and repeats the process from S30 again.

  In S40, when it is determined that the flatness is within the specified value, the treatment planning apparatus 100 transmits the treatment plan data to the control device 7 so that the treatment can be performed under the set conditions. In response, a signal is output (step S60). Thus, the process shown in FIG. 5 is completed.

  Next, operations and effects of the charged particle beam therapy system 1 according to this embodiment will be described.

  First, a charged particle beam therapy system according to a comparative example will be described with reference to FIG. In the charged particle beam therapy system according to the comparative example, the enlargement amount of the charged particle beam R is set to a predetermined size regardless of the size of the tumor 14 (for example, see also the irradiation region E2 in FIG. 3). In the charged particle beam therapy system, the charged particle beam R that is blocked by the multi-leaf collimator 24 is not used for irradiation of the tumor 14. Therefore, when the tumor 14 becomes small, a portion of the charged particle beam R that is shielded by the multi-leaf collimator 24 (portion indicated by A in the figure) increases, resulting in a problem that the dose is wasted. Furthermore, when the amount of enlargement of the charged particle beam R is large with respect to the tumor 14, the density of the charged particle beam R is relatively small. Further, when the irradiation field of the multi-leaf collimator 24 is small as compared with the amount of enlargement of the charged particle beam R, the penumbra may become large due to the distribution of the phase space of the particles.

  On the other hand, the charged particle beam therapy apparatus 1 according to the present embodiment is provided in the irradiation unit 8 and expands the charged particle beam R, and the irradiation range of the charged particle beam R according to the shape of the tumor 14. And a multi-leaf collimator 24 to be defined. Therefore, the vicinity of the outer edge of the charged particle beam R magnified by the magnifier 70 is shielded by the multi-leaf collimator 24, and the portion that has passed through the multi-leaf collimator 24 is irradiated to the tumor 14. Here, the charged particle beam therapy system 1 according to the present embodiment includes an enlargement amount adjustment unit 102 that adjusts the enlargement amount of the charged particle beam R by the enlargement unit 70 in accordance with the shape of the tumor 14. Thereby, for example, as shown in FIG. 6B, when the tumor 14 becomes small, the enlargement amount adjustment unit 102 can reduce the enlargement amount of the charged particle beam R accordingly. That is, in FIG. 3, what is irradiated in the irradiation region E2 at the other irradiation time can be reduced to the irradiation region E1 by reducing the enlargement amount. Therefore, the dose shielded by the multi-leaf collimator 24 in the charged particle beam R can be reduced. Furthermore, since the amount of enlargement of the charged particle beam R is reduced in accordance with the tumor 14, the density of the charged particle beam R can be relatively increased as compared with the case of FIG. Further, by reducing the amount of enlargement of the charged particle beam R in accordance with the irradiation field of the multi-leaf collimator 24, the occurrence of penumbra can be suppressed. As described above, the charged particle beam R can be efficiently irradiated according to the shape of the tumor 14.

  In the charged particle beam therapy system 1, the scattering unit 5 functioning as the magnifying unit 70 includes a plurality of scatterers 5a that diffuse the charged particle beam R, and the magnifying amount adjusting unit 102 adjusts the number of scatterers 5a. Thus, the amount of enlargement of the charged particle beam R may be adjusted. Thereby, the enlargement amount adjusting unit 102 can appropriately enlarge the charged particle beam R by adjusting the number of the scatterers 5 a according to the shape of the tumor 14.

  The present invention is not limited to the above-described embodiment.

  For example, in the above-described embodiment, the wobbler method is exemplified as the irradiation method of the charged particle beam therapy system 1, but the irradiation method is not particularly limited, and the method corresponds to the enlarged irradiation method for expanding the charged particle beam R. Any method may be adopted. For example, uniform scanning (scanning so that a beam narrower than the wobbler method is reciprocated linearly or a lattice-like locus is drawn) may be performed. Moreover, you may employ | adopt a laminated body method.

An example of the operation in the case of employing the layered substrate method will be described. In this case, as shown in FIG. 7, the enlargement amount adjusting unit 102 virtually divides the tumor 14 into a plurality of layers in the depth direction. In FIG. 7, the tumor 14 is divided into L _{1 to} L _N layers. The enlargement amount adjusting unit 102 adjusts the enlargement amount of the charged particle beam R irradiated to each layer. For example, when irradiating the layer L _{n and} when irradiating the layer L _N , the shape of the irradiation field is different, and the shape of the opening of the multi-leaf collimator 24 is also different. The amount of enlargement of the charged particle beam R is adjusted in accordance with the shape. As described above, the charged particle beam R can be efficiently irradiated according to the shape of each layer of the tumor 14.

  In this case, a control process as shown in FIG. 8 may be executed. That is, in S40, after setting for one layer is completed and it is determined that the flatness is within the specified value, the treatment planning apparatus 100 determines whether or not the setting for all layers is completed. Is determined (step S70). If it is determined in S70 that the treatment has not been completed, the treatment planning apparatus 100 determines the next layer, and performs the processes of S10 to S50 on the target layer. If it is determined in S70 that the process has been completed, the process proceeds to S60. Other processes in FIG. 8 are the same as the processes in FIG.

  DESCRIPTION OF SYMBOLS 1 ... Charged particle beam therapy apparatus, 2 ... Accelerator, 5 ... Scattering part, 5a ... Scattering body, 8 ... Irradiation part, 14 ... Tumor (irradiated body), 24 ... Multi-leaf collimator, 70 ... Expansion part, 102 ... Expansion Quantity adjustment part.

Claims (3)

An accelerator that accelerates charged particles and emits charged particle beams;
An irradiation unit for irradiating the irradiated body with the charged particle beam;
An enlarged portion provided in the irradiation unit and enlarging the charged particle beam;
A collimator for defining an irradiation range of the charged particle beam according to the shape of the irradiated object;
A charged particle beam therapy apparatus comprising: an enlargement amount adjustment unit that adjusts an enlargement amount of the charged particle beam by the enlargement unit in accordance with a shape of the irradiated body. The enlargement unit includes a plurality of scatterers that diffuse the charged particle beam,
The charged particle beam therapy apparatus according to claim 1, wherein the expansion amount adjustment unit adjusts the expansion amount of the charged particle beam by adjusting the number of the scatterers.   The enlargement amount adjustment unit adjusts the enlargement amount of the charged particle beam irradiated to each layer when the irradiated object is virtually divided into a plurality of layers in the depth direction, respectively. 2. The charged particle beam therapy apparatus according to 2.

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