JP4490198B2 - Particle beam irradiation equipment - Google Patents

Description

  The present invention relates to a particle beam irradiation apparatus, and more particularly to a particle beam irradiation apparatus for irradiating a charged particle beam used in a particle beam therapy apparatus or the like.

  In recent years, many studies have been made on particle beam therapy using protons and heavy particles as cancer therapy. The particle beam therapy method is a method of killing cancer cells by irradiating the cancer cells with particle beams emitted from an accelerator.

  In the conventional particle beam therapy system, in order to change the range (range) of the particle beam, a range shifter composed of a plurality of (for example, 8 to 10) acrylic plates that are independently operated is provided. Each plate is inserted on the beam trajectory by a pneumatic cylinder as necessary. In this way, the thickness of the entire range shifter is adjusted by inserting and removing the flat plate so that the total thickness of the flat plate of the range shifter inserted on the beam trajectory becomes a desired value (for example, Patent Document 1). reference.).

  Further, as an irradiation method that is currently being put to practical use as a highly accurate irradiation method, there is a method called a spot scanning method. In the spot scanning method, the irradiation spot is clearly divided and the irradiation position is scanned while the irradiation is stopped.

  As a device that realizes the spot scanning method, a set of scanning electromagnets that generate a scanning magnetic field consisting of a set of magnetic fields that bend the charged particle beam in the opposite direction by the same angle is mounted on a rotary drive gear that is rotated by a motor. Thus, there has been proposed one that realizes biaxial parallel beam scanning by rotating them (see, for example, Patent Document 2).

JP 2001-212253 A Japanese Patent Laid-Open No. 11-114078

  In the case of performing spot-scan irradiation as shown in Patent Document 2, it is necessary to change the range in a short time (100 msec or less) in order to shorten the irradiation time. In the conventional range shifter that takes in and out the flat plate as shown in Patent Document 1, it is necessary to drive a distance of about 200 mm, and in order to change the range in a short time of about 100 msec seconds, it is 2 m / sec or more. Therefore, it is necessary to insert a flat plate at a high speed, which requires a drive mechanism with a large driving force, and it is necessary to equip each range shifter with a large air cylinder and to put in and out the range shifter. It was.

  In addition, it is necessary to prepare a driving mechanism composed of a large air cylinder as described above for each flat plate of a range shifter normally composed of 8 to 10 flat plates, which increases costs. There was a problem.

  Further, when the range shifter is operated, a plurality of flat plates come and go at a high speed, and there is a problem that noise is generated.

  The present invention has been made to solve such a problem, and an object of the present invention is to obtain a particle beam irradiation apparatus capable of reducing the cost and reducing the range shifter driving sound.

The present invention is a particle beam irradiation apparatus for irradiating an irradiated body with a charged particle beam, and deflecting the charged particle beam to control a position in a planar direction inside the irradiated body. Means, a range shifter configured in a step shape for controlling the position in the depth direction inside the irradiated body by passing the deflected charged particle beam, each stage of the range shifter, and the irradiated Drive means for changing the relative position with the body, and the range shifter configured in the step shape is perpendicular to the direction in which the thickness change direction of the range shifter is larger in the scanning direction It is a particle beam irradiation apparatus installed as described above .

The present invention is a particle beam irradiation apparatus for irradiating an irradiated body with a charged particle beam, and deflecting the charged particle beam to control a position in a planar direction inside the irradiated body. Means, a range shifter configured in a step shape for controlling the position in the depth direction inside the irradiated body by passing the deflected charged particle beam, each stage of the range shifter, and the irradiated Drive means for changing the relative position with the body, and the range shifter configured in the step shape is perpendicular to the direction in which the thickness change direction of the range shifter is larger in the scanning direction since a particle beam irradiation apparatus that is installed so as, by using a stepwise range shifter, it is possible to reduce the range shifter driving noise, and suppress the device at a low cost Rukoto can.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a particle beam irradiation apparatus by a spot scanning method according to Embodiment 1 of the present invention. The particle beam irradiation apparatus according to the present invention is an apparatus for irradiating an irradiation region 7 in an irradiated pair 6 with a charged particle beam 2 emitted from a charged particle accelerator (not shown) or the like. As shown in FIG. 1, in the particle beam irradiation apparatus according to the present embodiment, a deflection electromagnet 1b having the same configuration is provided below the deflection electromagnet 1a. Here, 1a shows only the magnetic pole part of the deflection electromagnet, and the entire deflection electromagnet is composed of, for example, a magnetic pole 1a, a return yoke 101a and a coil 102a as shown in FIG. Similarly, 1b shows only the magnetic pole part of the deflection electromagnet, and the entire deflection electromagnet is composed of, for example, a magnetic pole 1b, a return yoke 101b and a coil 102b as shown in FIG. Further, a stepped range shifter 3 is provided below the deflection electromagnet 1b, and a position monitor 4 and a dose monitor 5 for monitoring the charged particle beam 2 are sequentially provided therebelow. The irradiated object 6 is placed below the dose monitor 5, and the irradiation region 7 in the irradiated object 6 is irradiated with the charged particle beam 2. As shown in FIG. 1, the stepped range shifter 3 has a thickness that changes in a stepped manner, and the charged particle beam 2 is positioned at any one of the steps configured in the stepped shape. This is for controlling the position in the depth direction inside the irradiated body 6 depending on whether the light is passed through.

  In the particle beam irradiation apparatus according to the present embodiment configured as described above, the charged particle beam 2 supplied from a charged particle accelerator (not shown) or the like is deflected by the deflecting electromagnets 1a and 1b, for example, An orbit 2a is formed to irradiate the irradiation region 7 inside the irradiated body 6. At this time, since the irradiation of the charged particle beam 2 is performed for each small region (spot) obtained by three-dimensionally dividing the irradiation region 7, the charged particle beam irradiation position is adjusted three-dimensionally to irradiate all spots. Do.

  The deflection electromagnets 1a and 1b are provided with excitation current supply means (not shown) for supplying an excitation current, thereby changing the excitation currents of the deflection electromagnets 1a and 1b, whereby the charged particle beam 2 Can be continuously moved from the track 2a to the track 2b. The excitation current value is adjusted and controlled by a scan control device 27 (see FIG. 3) described later. Furthermore, the irradiation position of the charged particle beam 2 in the plane perpendicular to the beam axis 9 can be controlled by rotating the deflection electromagnets 1 a and 1 b together with the beam axis 9. Thus, the deflection electromagnets 1 a and 1 b constitute beam position changing means for deflecting the charged particle beam 2 and controlling the position in the planar direction inside the irradiated body 6. Further, the thickness of the charged particle beam 2 passing through the range shifter 3 is adjusted (in a step shape) by moving the range shifter 3 configured in a step shape in the direction of arrow A in FIG. The position (range) in the depth direction can be controlled. Further, in irradiation to each spot, a position monitor 4 for monitoring the position of the charged particle beam 2 and a dose monitor 5 for monitoring the irradiation dose of the charged particle beam 2 are placed in front of the irradiated object 6. Since the charged particle beam 2 can be monitored by using these monitors 4 and 5, it is possible to confirm whether or not appropriate irradiation is being performed on the irradiated object 6. it can.

  The step-shaped range shifter 3 is made of a material such as acrylic, but the height of each step is the minimum unit required when dividing the irradiation region 7 in the depth direction. In normal spot scan irradiation, the division width in the depth direction is about 5 mm in water equivalent thickness. Therefore, if the minimum division unit is 5 mm, the level difference of each step of the range shifter 3 is 5 mm in water equivalent thickness. Set. In order to control the position in the depth direction with higher accuracy, the minimum unit may be 1 / N of the division width (N is an integer greater than 1).

  The detailed configuration will be described. As shown in FIG. 2, the stepped range shifter 3 is connected to the deflection electromagnets 1a and 1b via the frame 15 and the guide 16, and the deflection electromagnets 1a and 1b rotate. Has a structure that rotates together. In other words, the stepped range shifter 3 is supported at both ends by guides 16, and each guide 16 is provided with a substantially rectangular frame-shaped frame 15 protruding upward. Bending electromagnets 1 a and 1 b are installed between the frames 15. The stepped range shifter 3 is supported by a guide 16 but is fixed to the guide 16 in the beam axis direction and the beam scan direction, and is perpendicular to the beam axis and the beam scan direction (range shifter driving). In the direction, that is, the direction A in FIG.

  As shown in FIG. 3, the range shifter 3 is connected to a driving device 20 for driving the range shifter 3 in the direction A of FIG. The drive device 20 is electrically connected with a range shifter drive control device 25 for controlling the drive device 20. As described above, the driving device 20 constitutes driving means for changing (controlling) the relative position between each stage of the range shifter 3 and the irradiated object 6. A range shifter position reading device 26 for detecting the position of the range shifter 3 is provided below the range shifter 3, and a detection signal of the range shifter position reading device 26 is input to the range shifter drive control device 25. Further, a scan control device 27 is provided for adjusting the excitation current of the deflection electromagnets 1 a and 1 b and instructing the range shifter thickness to the range shifter drive control device 25.

  The operation in the configuration of FIG. 3 will be described. The range shifter 3 is driven in the range shifter driving direction by the driving device 20 via the member 21. The drive device 20 is composed of, for example, a linear motor, a stepping motor, or a servo motor. The range shifter drive control device 25 drives the drive device so that the position where the charged particle beam 2 is irradiated onto the range shifter 3 is approximately the center of the stage of the corresponding range shifter according to the required range shifter thickness. 20 is used to adjust the insertion amount of the range shifter 3. Further, the adjustment of the range shifter insertion amount can be further improved in accuracy by using the detection signal of the range shifter position reading device 26. The scan control device 27 performs adjustment of the excitation current of the deflection electromagnet 1 and commands the range shifter thickness to the range shifter drive control device 25 in accordance with a planned scan procedure.

  In such a configuration, even if the excitation current of the deflecting electromagnets 1a and 1b is changed and the electromagnets 1a and 1b are rotated to change the irradiation position of the charged particle beam 2 in a plane perpendicular to the beam axis 9, The region where the charged particle beam 2 passes through the stepped range shifter 3 is a rectangular region whose width is about the beam size and whose length is about the beam scan width by the deflecting electromagnets 1a and 1b. Therefore, as shown in FIG. 4, the width D of each step of the range shifter 3 configured in a staircase pattern is equal to the beam size S of the charged particle beam 2 at the position of the range shifter 3 (the beam diameter at the irradiation position 30). What is necessary is just to set larger than the maximum value Smax.

  As described above, irradiation of the irradiation region 7 is performed by changing the position of the charged particle beam 2 in the R direction by the excitation current of the deflecting electromagnets 1a and 1b, changing the range by the stepped range shifter 3, and rotating the deflecting electromagnets 1a and 1b. A combination of three changes in position in the θ direction is performed. As an irradiation procedure, the above three changes may be combined in an arbitrary order. However, when changing, a procedure that requires a lot of change time is set so that the number of changes is reduced. Time can be shortened. In the normal method, the change that can be made at the highest speed is the change in the beam position in the R direction due to the change in the excitation current of the deflection electromagnet 1, and the change in the rotation angle in the θ direction takes the most time. Therefore, the change procedure is as follows: 1) First, set the rotation angle and range (insertion amount of the range shifter 3), then make a series of changes in the R direction, and 2) change the range and then R again. A series of direction changes are repeated, 3) when all the range changes are completed, the rotation angle is changed, and 4) 1), 2) and 3) are repeated again. This procedure is shown in FIG.

  That is, as shown in FIG. 5, first, the rotation angle of the deflecting electromagnets 1a and 1b in the θ direction is set (step S1), then the position of the stepped range shifter 3 is changed (step S2), and then The position of the charged particle beam 2 in the R direction is changed (step S3). Next, it is determined whether or not the position change of the charged particle beam 2 in the R direction has been completed (step S4). If completed, the process proceeds to step S5, and if not completed, the process returns to step S3. In step S5, it is determined whether or not the change of the position of the stepped range shifter 3 has been completed (step S5). If completed, the process proceeds to step S6, and if not completed, the process returns to step S2. In step S6, it is determined whether or not the rotation angle of the deflection electromagnet 1 in the θ direction has been completed (step S5). If completed, the process is terminated, and if not completed, the process returns to step S1.

  When the above irradiation procedure is reviewed by the operation of a specific apparatus, as shown in FIG. 6, when the corresponding position on the range shifter 3 with respect to the irradiation position of the first spot is 30a (range shifter thickness When the position of the range shifter 3 is fixed, the exciting currents of the deflection electromagnets 1a and 1b are changed, and irradiation is sequentially performed with 30b, 30c,. When the irradiation of is completed, the range shifter 3 is driven to move the position of the charged particle beam 2 to the next stage. The amount of movement of the range shifter 3 at this time is equal to the step width D. Subsequently, the excitation current is changed so that the deflecting electromagnets 1a and 1b move in the opposite direction, the spot irradiation is sequentially performed, and the range shifter 3 is further moved by D to move to the next stage. become. When all the changes of the range shifter 3 are completed (when the irradiation with the thickest range shifter thickness is completed), the rotation angle is changed, and this time, starting from the condition where the range shifter condition is the thickest, After the end of irradiation, the range shifter 3 is driven so as to reduce the thickness of the range shifter sequentially.

  Of course, the procedure may be such that the range shifter 3 is always driven so as to change from a thin condition to a thick condition.

  According to such a configuration, the driving device 20 of the range shifter 3 can be configured by only one driving device 20, and the cost of the system can be reduced. In addition, since the drive device 20 has a simple configuration, the maintainability is good and the overall weight is reduced. Moreover, since it is composed of only one driving device, the size of the entire range shifter in the beam axis direction can be reduced.

  The amount of movement of the range shifter 3 when changing the range of the charged particle beam 2, that is, the width of each stage of the range shifter 3 may be about the beam size of the charged particle beam 2, or about several times its size. If it is a particle beam apparatus, it can be set as about 10 mm-20 mm. For this reason, it becomes a driving distance of about 1/10 compared with 180 mm to 200 mm which is the movement amount of the conventional range shifter driving device, and the range can be changed in a short time. Moreover, since the moving speed of the range shifter 3 can be reduced by shortening the driving distance, it is possible to construct a driving mechanism using an inexpensive motor and reduce the driving sound of the range shifter 3. I can do things. Further, since the number of drive mechanisms is reduced, the cost can be reduced as a whole even if a high-performance drive mechanism is used.

  As described above, in the present embodiment, the range shifter according to the present invention is used for spot scan irradiation by the parallel beam scan method, and one range shifter configured in a step shape is synchronized with the scan irradiation. Drive. Since the moving distance of the range shifter is short, the moving speed can be lowered, a motor with a small torque can be used, and the cost of the apparatus can be reduced. Further, since the number of range shifters to be driven is reduced, the cost can be reduced by reducing the number of driving devices. Further, since only one range shifter is operated during irradiation and the speed change of the range shifter is small, noise accompanying the driving of the range shifter can be reduced.

Embodiment 2. FIG.
FIG. 7 is a configuration diagram showing the configuration of the particle beam irradiation apparatus according to the second embodiment. In the present embodiment, as shown in FIG. 7, the parallel scan type electromagnet constituted by the two deflection electromagnets 1 a and 1 b in the configuration of the first embodiment is constituted by only one deflection electromagnet 1. . In this configuration, since the incident angle of the charged particle beam 2 to the irradiated body 6 is oblique, the lateral width of the step range shifter 3 can be reduced. Since other configurations are the same as those in the first embodiment, the same reference numerals are given and description thereof is omitted here.

  As described above, in the second embodiment, the same effect as in the first embodiment can be obtained, and further, only one deflection electromagnet is configured. Since the incident angle of the beam 2 on the irradiated body 6 is inclined, the lateral width of the stepped range shifter 3 can be reduced, the weight of the range shifter 3 can be reduced, and the cost of the range shifter driving mechanism can be reduced. Furthermore, the cost can be reduced by the amount of the decrease in the number of deflection electromagnets.

Embodiment 3 FIG.
FIG. 8 is a configuration diagram showing the configuration of the range shifter of the particle beam irradiation apparatus according to the third embodiment. In the present embodiment, as shown in FIG. 8, the range shifter 3 is composed of two range shifters, that is, a range shift range shifter 3a at the time of scanning irradiation and a rough range change range shifter 3b. In addition, although the width | variety of each step | level of each range shifter 3a and 3b is the same, as shown in FIG. 8, the thickness of the range shifter 3b becomes larger than the thickness of the range shifter 3a. ing. Since other configurations are the same as those in the first or second embodiment, the same reference numerals are given, and the description thereof is omitted here.

In normal particle beam therapy, the maximum thickness of the irradiated object 6 is about 30 cm in terms of water equivalent thickness, while the maximum thickness of the irradiation region 7 is about 14 cm in terms of water equivalent thickness. Therefore, in one irradiation, the range shifter thickness corresponding to the maximum range is roughly determined by the range shifter 3b, and at the time of spot scanning, the range shifter 3b is fixed and only the range shifter 3a is driven, and the range during irradiation Make changes. The height Δh ′ of each step of the range shifter 3b is equal to the maximum thickness h _{max of} the range shifter 3a and the height Δh of each step of the range shifter 3a.
Δh <Δh ′ <h _max / 2
To be configured.

  With such a configuration, it is not necessary for the range shifter 3a to correspond to the maximum thickness of the irradiated object 6, and at least corresponds to the maximum thickness of the irradiation region 7. As a result, the mass of the range shifter 3a driven at high speed can be reduced, so that the cost of the driving device, the improvement of the driving speed, and the driving sound can be reduced. Further, the range shifter 3b may be a method of inserting a plurality of conventional flat plates. There is no problem in driving the range shifter 3b even in low-speed driving that moves in several seconds to several tens of seconds, so there is no need to provide a large driving mechanism, and the cost can be reduced even if a plurality of driving mechanisms are arranged.

  As described above, in the present embodiment, the same effects as those of the first embodiment can be obtained, and furthermore, the range change range shifter 3a at the time of scanning irradiation and the rough range change range shifter 3b. Since the mass of the range shifter 3a driven at high speed can be reduced, the cost of the driving device, the improvement of the driving speed, and the driving sound can be reduced.

Embodiment 4 FIG.
FIG. 9 is a configuration diagram showing the configuration of the range shifter of the particle beam irradiation apparatus according to the fourth embodiment. In FIG. 9, the range D of the range shifter 3 b disposed on the upstream side of the charged particle beam 2 in the range shifter configured by the range change range shifter 3 a and the rough range change range shifter 3 b at the time of scanning irradiation. For the width D ′ of the stage of the range shifter 3a arranged downstream,
D ′ ≧ D + ΔS
It comprised so that it might become. Here, ΔS is defined by the difference between the beam size S of the charged particle beam 2 before entering the range shifter 3a and the beam size S ′ of the charged particle beam 2 immediately after exiting the range shifter 3b. Since the beam size of the charged particle beam 2 is enlarged by scattering when passing through the range shifters 3a and 3b, normally S <S ′.
ΔS = S′−S
It is. The width D ′ of each stage of the range shifter 3b may be determined so as to satisfy D ′ ≧ D + ΔS for each stage, and all stages so that D ′ ≧ D + ΔSmax is satisfied with respect to the maximum value ΔSmax of ΔS. The same width may be used. Other configurations are the same as those in the third embodiment, and are denoted by the same reference numerals, and the description thereof is omitted here.

  With such a configuration, the charged particle beam is scattered in the range shifters 3a and 3b, so that the beam size in the vicinity of the lower surface of the range shifter 3b is expanded and the charged particle beam is prevented from entering the steps having different thicknesses. it can.

  As described above, in the present embodiment, the same effects as in the first to third embodiments can be obtained, and moreover than the width D of the stage of the range shifter 3b disposed on the upstream side of the charged particle beam 2 Since the width D ′ of the step of the range shifter 3a arranged downstream is made larger, the beam size in the vicinity of the lower surface of the range shifter 3b is increased by scattering of the charged particle beam in the range shifters 3a and 3b, and the charge is charged. The particle beam can be prevented from entering the steps having different thicknesses, and the range of the charged particle beam can be prevented from changing.

Embodiment 5 FIG.
FIG. 10 is a configuration diagram showing the configuration of the particle beam irradiation apparatus according to the fifth embodiment. In FIG. 10, the range shifter 3 is composed of three range shifters: a range shifter 3a for changing the range at the time of scanning irradiation, a range shifter 3b for changing the rough range, and a detailed range shifter 3c for adjusting the range. The width of each stage of each range shifter 3a, 3b, 3c is the same. The thickness of each corresponding step is the largest in the range shifter 3b, the next is the range shifter 3a, and the smallest is the range shifter 3c. Other configurations are the same as those in the first embodiment, and are denoted by the same reference numerals, and description thereof is omitted here.

  In the fifth embodiment, when the height Δh ″ of each stage of the range shifter 3c is Δh, the value Δh ″ = Δh / divided by an integer N greater than 1 N, and the number of stages of the range shifter 3c is N-1 or more. Like the range shifter 3a, the range shifter 3c is driven to a predetermined position once before the start of scanning irradiation, and is not driven during scanning irradiation.

  With such a configuration, the thickness of the range shifter 3 can be set in detail, and the range of the charged particle beam 2 can be adjusted in detail. Further, the number of stages of the range shifter 3a can be reduced. As a result, the size / weight of the range shifter 3a can be reduced, the cost of the drive mechanism can be reduced, and the drive sound can be reduced.

  As described above, in the fifth embodiment, the same effects as those of the first embodiment can be obtained. Further, the range shifter 3 is replaced with a range changer 3a for changing the range at the time of scanning irradiation, and a rough range change. The range shifter 3b and the detailed range adjustment range shifter 3c are used, so that the range adjustment can be made in detail, and the number of stages of the range shifter 3a can be reduced at the same time. The size / weight of the range shifter 3a can be reduced, the cost of the drive mechanism can be reduced, and the drive sound can be reduced.

Embodiment 6 FIG.
FIG. 11 is a configuration diagram showing the configuration of the range shifter of the particle beam irradiation apparatus according to the sixth embodiment. In the sixth embodiment, as shown in FIG. 11, a beam position measuring strip electrode 40 (hereinafter referred to as a signal electrode 40) is disposed on the back surface of the range shifter 3. As shown in FIG. 11, the signal electrode 40 is provided in a direction parallel to each stage of the range shifter 3. The signal electrode 40 is formed of a thin conductive film member such as copper or aluminum, and the electrodes are insulated from each other. Usually, since the range shifter 3 is formed of an insulating member such as acrylic, the signal electrode 40 can be directly formed on the range shifter 3 by a method such as vapor deposition or etching. When the range shifter 3 is formed of a conductive member, an insulating member such as polyimide is formed on the surface of the range shifter, and the signal electrode 40 may be disposed thereon.

  In this configuration, in the present embodiment, as shown in FIG. 12, the high voltage electrode 41 is disposed at a position facing the signal electrode 40 and spaced apart from the signal electrode 40 by a predetermined interval. A voltage of about 1 kV to 5 kV is applied to the high voltage electrode 41. The signal electrode 40 is arranged so as to have a ground potential, and an ion having a charge generated by the charged particle beam 2 ionizing air is applied to the signal electrode 40 immediately adjacent to the position where the charged particle beam 2 has passed. Or, electrons are collected. For this reason, an electrical signal is generated at the signal electrode 40 at the position where the charged particle beam 2 has passed. Thereby, it is possible to accurately detect which stage of the range shifter 3 the charged particle beam 2 has passed.

  Beam position information can be obtained by processing the electrical signal of the signal electrode 40 by a signal processing circuit 45 as shown in FIG. This position information is sent to the range shifter drive control device 25 to adjust the position of the range shifter 3 with high accuracy. In addition, position information is sent to the scan control device 27 to detect a change in the position of the charged particle beam due to a trouble of the device, and this is a safety function for stopping the charged particle beam irradiation procedure.

  With such a configuration, the position of the range shifter is detected with respect to the actual beam, so that the position of the range shifter can be adjusted more accurately. In addition, when a beam misalignment occurs due to a trouble in the apparatus, an interlock function can be provided, and safer beam irradiation can be performed.

  As described above, in the present embodiment, the same effects as those of the first embodiment can be obtained, and the signal electrode 40 for measuring the beam position is attached to one surface of the range shifter 3. Thus, it is possible to construct a safe system even when the beam position or the range shifter position becomes abnormal due to equipment trouble.

Embodiment 7 FIG.
FIG. 14 is a configuration diagram showing the configuration of the particle beam irradiation apparatus according to the second embodiment. FIG. 14 is a diagram in which the driving method of the range shifter 3 as shown in the first to sixth embodiments is changed from a step operation that repeats stationary and driving to a constant driving method that always moves at a substantially constant speed. That is, in the present embodiment, the range shifter 3 moves at a substantially constant speed during the irradiation of the charged particle beam by spot scanning, and the beam irradiation position on the range shifter 3 is on the range shifter 3 as shown in FIG. Move diagonally. The moving speed of the range shifter 3 is adjusted so that the charged particle beam 2 is sufficiently contained in one stage during the position change of the charged particle beam 2 in the R direction.

When the scanning time of the charged particle beam 2 in the R direction is t1, the time when the range shifter 3 moves to the next stage is t2, and the beam size at the position of the range shifter is S, the moving speed v of the range shifter 3 is
v = S / t2
Is set. The distance d1 that the range shifter 3 moves during scanning in the R direction is
d1 = v × t1
It becomes. At this time, the width D of each stage of the range shifter 3 is
D = d1 + S = S / t2 × t1 + S = S × (t1 + t2) / t2
Determine as. The driving speed v of the range shifter 3 is
v = D / (t1 + t2) = (DS) / t1
It can also be expressed.
Here, as S, S ′ obtained by adding a beam position variation error to the beam size may be used.

  For example, if t1 = 100 msec, t2 = 50 msec, and S = 10 mm, then D = 30 mm and v = 0.2 m / sec. As a driving speed, a normal motor driving method or a linear motor driving method can be used. .

  Moreover, since the irradiation time of the charged particle beam 2 by spot scanning differs for each irradiation, the scanning time t1 varies for each irradiation. For this reason, t1 may be set to a sufficiently large value that can absorb fluctuations in scan time.

  Further, the fluctuation of t1 may be corrected by adjusting the driving speed v of the range shifter 3. At this time, the electrode position of the beam position measuring electrode 40 shown in the fifth embodiment is rotated 90 degrees and attached so that the position in the scanning direction of the beam can be measured. Based on the position, the range shifter drive control device 25 may adjust the range shifter drive speed.

  With such a configuration, the driving speed of the range shifter 3 can be made almost constant, so that driving noise can be reduced. Moreover, a motor or a linear motor can be applied as the drive mechanism, and a low-cost drive mechanism can be configured.

  As described above, in the seventh embodiment, the same effects as in the first to sixth embodiments can be obtained, and the range shifter 3 can be driven at a substantially constant speed as the driving method of the range shifter 3. Therefore, the driving sound of the range shifter 3 can be reduced and the range can be changed at high speed.

Embodiment 8 FIG.
In the eighth embodiment, as shown in FIG. 15, in the range shifter driving system having the configuration of the seventh embodiment, the deflecting electromagnet with respect to the beam irradiation range W on the range shifter 3 corresponding to the irradiation region. When the maximum scanable range of 1 is Wmax, the driving speed v of the range shifter 3 is
v = (D−S ′) / t1 × Wmax / W
It was.

  Although the actual beam range W is smaller than the maximum scannable range Wmax, the scan range of the deflection electromagnet 1 is generally always set to Wmax due to the problem of the hysteresis characteristics of the deflection electromagnet 1. Therefore, at the time when the deflecting electromagnet 1 scans outside the beam irradiation range W, the beam position may approach the stepped portion of the range shifter 3, and DS ′ is capable of beam irradiation in the driving direction of the range shifter 3. And the irradiation range W in the scanning direction need only match. If the moving speed v of the range shifter 3 is set to the above value, both can be matched.

At this time, the time required for the range shifter 3 to move by the width D of the stage of the range shifter 3 is
t = D / v = D / (DS ′) × t1 × W / Wmax
The effective value t2 of the range change time is
t2 = t−t1 = t1 × (D / (DS ′) × W / Wmax−1)
t2 = t1 × (S′−D × (1−W / Wmax)) / (DS−S ′)
Thus, the range change time t2 = t1 × S ′ / (DS ′) in the driving method of the seventh embodiment can be made shorter.

In particular, as shown in FIG.
W / Wmax <S '/ D
If
v = D / t1
By doing so, the effective range change time can be made zero.

  As described above, in the eighth embodiment, the same effects as in the first to sixth embodiments can be obtained, and the range shifter 3 can be driven at a substantially constant speed as the driving method of the range shifter 3. Therefore, the driving sound of the range shifter 3 can be reduced and the range can be changed at high speed.

Embodiment 9 FIG.
FIG. 17 is a configuration diagram showing the configuration of the particle beam irradiation apparatus according to the ninth embodiment. As shown in FIG. 17, in the particle beam irradiation apparatus according to the ninth embodiment, a deflection electromagnet 1b having the same configuration is provided below the deflection electromagnet 1a. Here, 1a shows only the magnetic pole part of the deflection electromagnet, and the entire deflection electromagnet is composed of, for example, a magnetic pole 1a, a return yoke 101a and a coil 102a as shown in FIG. Similarly, 1b shows only the magnetic pole part of the deflection electromagnet, and the entire deflection electromagnet is composed of, for example, a magnetic pole 1b, a return yoke 101b and a coil 102b as shown in FIG. However, in the present embodiment, unlike the first embodiment described above, the deflecting electromagnets 1a and 1b are rotated 90 degrees. Further, a stepped range shifter 3 is provided below the deflection electromagnet 1b. The irradiated body 6 is below the stepped range shifter 3, and the charged particle beam 2 is irradiated to the irradiation region 7 in the irradiated body 6. Also in this embodiment, the position monitor 4 and the dose monitor 5 shown in the first embodiment may be provided.

  As described above, the particle beam irradiation apparatus according to the present embodiment has a configuration using the stepped range shifter 3 in the spot scan irradiation apparatus of the XY scan method. In the XY scan method, the deflecting electromagnets 1a and 1b are rotated by 90 degrees, and the charged particle beam 2 is scanned in a plane (XY plane) perpendicular to the beam axis 9 as shown in FIG.

When the step width at the time of scanning in the Y direction is Dy, the beam size is S, the beam size considering the beam misalignment error is S ′, and the beam scanning time in the X direction is t1, the step of the stepped range shifter 3 Width is D as D = Dy + S '
The moving speed v of the range shifter is v = Dy / t1
Then, when scanning the XY plane as shown in FIG. 18, in one stage of the range shifter 3, the charged particle beam 2 is placed on one diagonal line of the stage as shown in FIG. Is scanned along the short side, and then the charged particle beam 2 is scanned on the other diagonal (ie, scanned in an X-shape). When one scan of the XY plane is completed, the moving direction of the range shifter 3 is reversed, and at the same time, the stage irradiated with the beam is shifted by one stage and the driving is resumed.

  According to such a configuration, it is possible to reduce the operation sound of the range shifter 3 and the cost of the driving mechanism in the XY scan type spot scan irradiation apparatus.

  As described above, in the ninth embodiment, the same effects as those of the first embodiment can be obtained, and the deflecting electromagnets 1a and 1b are rotated by 90 degrees to place the charged particle beam 2 as a beam. In the plane perpendicular to the axis 9 (XY plane), scanning is performed in an X shape as shown in FIG. 17, so in the spot scan irradiation apparatus of the XY scan method, the operation sound of the range shifter 3 is reduced. It becomes possible to reduce the cost of the drive mechanism.

Embodiment 10 FIG.
FIG. 19 is a configuration diagram showing the configuration of the particle beam irradiation apparatus according to the tenth embodiment. As shown in FIG. 19, in the particle beam irradiation apparatus according to the tenth embodiment, a stepped range shifter 3 is provided below the deflection electromagnet 41. Below that, a position monitor 4 for monitoring the position of the charged particle beam 2 and a dose monitor 5 for monitoring the irradiation dose are provided. The irradiated body 6 is below the dose monitor 5, and the charged particle beam 2 is irradiated to the irradiation region 7 in the irradiated body 6. The irradiated body 6 is disposed on the bed 42.

  In the tenth embodiment, the stepped range shifter 3 is used in the particle beam irradiation apparatus configured to be able to deflect the charged particle beam position in the deflection electromagnet 41 arranged upstream of the scan irradiation apparatus. It is. By adjusting the excitation current of the upstream deflection electromagnet 41, the charged particle beam 2 is scanned in the X direction. Thus, the deflection electromagnet 41 constitutes beam position changing means for deflecting the charged particle beam 2 and controlling the position in the planar direction inside the irradiated body 6.

  On the other hand, the irradiated body 6 is arranged or fixed on the bed 42, and the bed 42 is configured to be movable in the Y direction by a drive mechanism (not shown). In this way, the bed 42 is an irradiation object mounting means that is movably provided for mounting the irradiation object 6, and changes the relative position between each stage of the range shifter 3 and the irradiation object 6. The drive means for (control) is comprised. By scanning or driving the deflection electromagnet 41, the bed 42, and the range shifter 3, respectively, the irradiation region 7 is scanned and irradiated three-dimensionally.

  The scanning procedure is efficient in that the scanning in the X direction is performed first, then the range shifter 3 is driven, and finally the bed 42 is moved in the Y direction, but other procedures such as the X direction, the Y direction, The order of the range shifter 3 may be used.

  According to such a configuration, in the particle beam irradiation apparatus configured such that the position of the charged particle beam 2 can be deflected by the deflection electromagnet 41 disposed upstream of the scan irradiation apparatus, the operation sound of the range shifter 3 is reduced and driven. The cost of the mechanism can be reduced.

  As described above, in the tenth embodiment, the same effect as in the first embodiment can be obtained, and the charged particle beam 2 can be moved in the X direction by adjusting the excitation current of the deflection electromagnet 41. Since the irradiated object 6 is configured to be moved in the Y direction by the bed 42 while being scanned, the driving sound of the range shifter 3 is reduced and the size in the axial direction is reduced, so that the irradiation is performed. It is possible to reduce the size of the entire apparatus in the axial direction.

Embodiment 11 FIG.
A stepped range shifter can also be used for a particle beam irradiation apparatus provided with a deflecting electromagnet or beam deflection means arranged upstream of the scanning irradiation apparatus.

Embodiment 12 FIG.
In the first to eleventh embodiments, the example using the stepped range shifter has been described. However, the same effect can be obtained by using a mountain range shifter in which two stepped range shifters are coupled back to back. be able to. In the first to eleventh embodiments, when the driving device 20 moves from the lowermost stage to the uppermost stage of the stepped range shifter 3, it is necessary to change the driving direction in the reverse direction. Since the range shifter is configured in a mountain shape, it can move again from the uppermost stage to the lowermost stage in the same driving direction after moving from the lowermost stage to the uppermost stage, so the number of changes in the driving direction of the range shifter by the driving device 20 Can be reduced.

Embodiment 13 FIG.
In the first to eleventh embodiments, the example in which the irradiation position of the charged particle beam 2 is measured by the position monitor 4, the dose monitor 5, the signal electrode 40 for position measurement, and the like has been described. In the present embodiment, an example in which a sub-dose monitor is further described.

  The auxiliary dose monitor is a line type dose monitor. The trajectory of the charged particle beam 2 moves along a preset pattern, as shown in FIG. 6 and FIGS. Therefore, in this embodiment, a line-type sub-dose monitor is installed along the pattern. Accordingly, the line-type sub-dose monitor is arranged so as to always coincide with the beam irradiation point of the charged particle beam 2. In this configuration, by comparing the value of the dose monitor 5 as the main dose monitor with the value of the line-type sub-dose monitor in the present embodiment, it is possible to further accurately determine that the beam position is correctly controlled. Can be confirmed.

It is the block diagram which showed the structure of the particle beam irradiation apparatus which concerns on Embodiment 1 of this invention. It is the elements on larger scale which showed the structure of the particle beam irradiation apparatus which concerns on Embodiment 1 of this invention. It is the block diagram which showed the structure of the particle beam irradiation apparatus which concerns on Embodiment 1 of this invention. It is the partial expansion perspective view which showed the structure of the particle beam irradiation apparatus which concerns on Embodiment 1 of this invention. It is the flowchart which showed operation | movement of the particle beam irradiation apparatus which concerns on Embodiment 1 of this invention. It is explanatory drawing which showed operation | movement of the particle beam irradiation apparatus which concerns on Embodiment 1 of this invention. It is the block diagram which showed the structure of the particle beam irradiation apparatus which concerns on Embodiment 2 of this invention. It is explanatory drawing which showed operation | movement of the particle beam irradiation apparatus which concerns on Embodiment 3 of this invention. It is explanatory drawing which showed operation | movement of the particle beam irradiation apparatus which concerns on Embodiment 4 of this invention. It is explanatory drawing which showed operation | movement of the particle beam irradiation apparatus which concerns on Embodiment 5 of this invention. It is the expansion perspective view which showed the structure of the range shifter of the particle beam irradiation apparatus which concerns on Embodiment 6 of this invention. It is explanatory drawing which showed operation | movement of the particle beam irradiation apparatus which concerns on Embodiment 6 of this invention. It is the block diagram which showed the structure of the particle beam irradiation apparatus which concerns on Embodiment 6 of this invention. It is explanatory drawing which showed operation | movement of the particle beam irradiation apparatus which concerns on Embodiment 7 of this invention. It is explanatory drawing which showed operation | movement of the particle beam irradiation apparatus which concerns on Embodiment 8 of this invention. It is explanatory drawing which showed operation | movement of the particle beam irradiation apparatus which concerns on Embodiment 8 of this invention. It is the block diagram which showed the structure of the particle beam irradiation apparatus which concerns on Embodiment 9 of this invention. It is explanatory drawing which showed operation | movement of the particle beam irradiation apparatus which concerns on Embodiment 9 of this invention. It is the block diagram which showed the structure of the particle beam irradiation apparatus which concerns on Embodiment 10 of this invention. It is explanatory drawing which showed the structure of the whole deflection electromagnet in the particle beam irradiation apparatus concerning Embodiment 1-9 of this invention. It is explanatory drawing which showed the structure of the whole deflection electromagnet in the particle beam irradiation apparatus concerning Embodiment 1-9 of this invention.

Explanation of symbols

  1, 1a, 1b Bending electromagnet, 2 charged particle beam, 3 stepped range shifter, 4 position monitor, 5 dose monitor, 6 irradiated object, 7 irradiation area, 9 beam axis, 15 frame, 16 guide, 20 drive device, 21 Members, 25 range shifter drive control device, 26 range shifter position reading device, 27 scan control device, 40 beam position measuring strip electrode (signal electrode), 41 high voltage electrode.

Claims (7)

A particle beam irradiation apparatus for irradiating an irradiated body with a charged particle beam,
Beam position changing means for deflecting a charged particle beam and controlling a position in a planar direction inside the irradiated body;
A range shifter configured in a step shape to control the position in the depth direction inside the irradiated object by passing the deflected charged particle beam; and
Drive means for changing the relative position between each stage of the range shifter and the irradiated object,
The step-shaped range shifter is installed such that the thickness change direction of the range shifter is perpendicular to the direction in which the width in the scanning direction is larger.   2. The particle beam irradiation apparatus according to claim 1, wherein the range shifter is provided with a beam position measuring electrode for measuring the position of the charged particle beam.   3. The particle according to claim 1, wherein the driving unit controls the range shifter to continue to move at a constant speed in synchronization with a beam position of the charged particle beam that passes through the particle beam during irradiation. X-ray irradiation device. A particle beam irradiation apparatus for irradiating an irradiated body with a charged particle beam,
A parallel beam scanner configured by a pair of deflection electromagnets arranged vertically in the beam axis direction, deflecting a charged particle beam and controlling the position in the planar direction inside the irradiated body;
By passing the deflected the charged particle beam, a range shifter configured stepwise to control the position in the depth direction of the inside of the irradiation object,
Drive means for changing the relative position between each stage of the range shifter and the irradiated object ;
The step shift range shifter is installed such that the thickness change direction of the range shifter is perpendicular to the beam scan direction of the parallel beam scanner, and can be rotated in synchronization with the parallel beam scanner. A particle beam irradiation apparatus characterized by comprising: A particle beam irradiation apparatus for irradiating an irradiated body with a charged particle beam,
A beam scanner that is composed of a single deflection electromagnet, deflects a charged particle beam, and controls the position in the planar direction inside the irradiated body;
By passing the deflected the charged particle beam, a range shifter configured stepwise to control the position in the depth direction of the inside of the irradiation object,
Drive means for changing the relative position between each stage of the range shifter and the irradiated object ;
The step-shaped range shifter is installed so that the thickness change direction of the range shifter is perpendicular to the beam scanning direction of the beam scanner, and can be rotated in synchronization with the beam scanner. A particle beam irradiation apparatus characterized by that.   6. The particle beam irradiation apparatus according to claim 4, wherein a beam position measuring electrode for measuring the position of the charged particle beam is provided on the range shifter. Before SL drive means, during the irradiation, in synchronism with the beam position of the charged particle beam passing through, any one of 4 claims, characterized in that control to continue to move the range shifter at a constant rate of 6 2. The particle beam irradiation apparatus according to item 1.

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