JP4591590B2 - Particle beam irradiation apparatus and particle beam therapy apparatus - Google Patents

Description

  The present invention relates to a particle beam irradiation apparatus for irradiating an irradiated body with a charged particle beam supplied from a particle accelerator, and a particle beam therapy apparatus using the particle beam irradiation apparatus.

  A conventional particle beam irradiation device that uses a range shifter that changes the range of the charged particle beam in the irradiated body, in order to reduce the change in the beam diameter of the charged particle beam due to scattering with the range shifter, A range shifter is disposed in the vicinity of the irradiated object, and further, a scatterer device or a quadrupole electromagnet as a beam scatterer is disposed upstream of the range shifter in the beam traveling direction (see, for example, Patent Document 1) or beam collimator. A meter was arranged (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 2001-212253 (paragraph 0053, FIG. 1) JP 2001-562 A (paragraph 0025, FIG. 7)

Since the conventional particle beam irradiation apparatus is configured as described above, the range shifter had to be arranged in the vicinity of the irradiated object, but in the case of a treatment apparatus that irradiates the patient's head and neck, the patient Due to the spatial interference with the shoulder of the body, the range shifter cannot be brought close enough to the irradiation site, and the beam diameter of the charged particle beam cannot be reduced to a required value.
In addition, since the range shifter whose thickness needs to be changed during the treatment is arranged in the vicinity of the patient, there is a problem that the patient is intimidated by moving sound or the like particularly when the range shifter is driven at high speed.
In addition, the beam diameter in the irradiated object is almost determined by the contribution of the range shifter and the scattering in the irradiated object, so the quadrupole electromagnet or beam collimator placed upstream of the range shifter beam travel direction should reduce the beam diameter. However, in the conventional apparatus, it was only possible to control in the direction of increasing the beam diameter.

  The present invention has been made to solve the above-described problems, and reduces the increase in the beam diameter of the charged particle beam due to scattering by the range shifter, so that the object to be irradiated is spatially precise. A particle beam irradiation apparatus and a particle beam therapy apparatus capable of supplying a charged particle beam having a small possible beam diameter and disposing a range shifter at a position away from a patient to eliminate the intimidation caused by the moving sound or the like The purpose is to obtain.

  The particle beam irradiation apparatus according to the present invention includes a variable range shifter that reduces the energy of the charged particle beam, and an excitation amount that is controlled according to the energy of the charged particle beam that is decreased by the variable range shifter. A quadrupole electromagnet that converges the divergence of the charged particle beam caused by the beam and a scanning electromagnet that changes the beam trajectory of the charged particle beam.

  According to the particle beam irradiation apparatus according to the present invention, the beam diameter on the irradiated object can be made smaller than that of the conventional method, and the irradiated object can be irradiated with spatial precision, and the range shifter can be used. Can be placed away from the irradiated object.

Embodiment 1 FIG.
Hereinafter, a particle beam irradiation apparatus according to Embodiment 1 of the present invention and a particle beam therapy apparatus including the particle beam irradiation apparatus, a particle accelerator, and a beam transport system will be described with reference to FIG.
In FIG. 1, a charged particle beam generated by a particle accelerator 1 is guided to a particle beam irradiation device 3 by a beam transport system 2 and first passes through an acrylic plate to reduce the energy of the charged particle beam. Pass 4 A quadrupole electromagnet 6 that reduces an increase in the beam diameter of the charged particle beam due to scattering by the variable range shifter 4 is disposed between the variable range shifter 4 and the irradiated object 5. Between the variable range shifter 4 and the quadrupole electromagnet 6, a fixed beam slit 7 having a fixed aperture diameter that restricts an increase in the divergence angle of the charged particle beam is disposed, and the quadrupole electromagnet 6 and the irradiated object 5 A scanning electromagnet 8 for changing the beam trajectory, a beam dose monitor 9, and a beam position monitor 10 are disposed between them.
Further, the thickness of the acrylic plate of the variable range shifter 4 and the magnetic field strengths of the quadrupole electromagnet 6 and the scanning electromagnet 8 are controlled by the irradiation control device 11.

Next, the operation of the particle beam irradiation apparatus will be described.
The charged particle beam guided from the particle accelerator 1 to the variable range shifter 4 by the beam transport system 2 passes through the acrylic plate by the variable range shifter 4 to reduce energy. The variable range shifter 4 is composed of, for example, a plurality of acrylic plates having different thicknesses, and the combination of these acrylic plates is changed, or the position where the charged particle beam passes is changed by a wedge-shaped acrylic plate. By doing so, it is possible to change the thickness of the acrylic plate through which the charged particle beam passes, thereby adjusting how much the energy of the particle beam is reduced.

  On the other hand, the beam diameter of the charged particle beam increases due to scattering by the variable range shifter 4. The fixed beam slit 7 limits an increase in the divergence angle of the charged particle beam due to scattering by the variable range shifter 4. Since charged particles having a large divergence angle are removed by the fixed beam slit 7, activation of the equipment downstream of the fixed beam slit 7 in the beam traveling direction is prevented.

  Further, the irradiation of the irradiated object 5 in the direction orthogonal to the beam traveling direction changes the course of the charged particle beam by the scanning electromagnet 8 while keeping the thickness of the variable range shifter 4 and the excitation amount of the quadrupole electromagnet 6 constant. And do it. Once irradiation in the direction orthogonal to the beam traveling direction is completed, the irradiation controller 11 changes the thickness of the variable range shifter 4 and the excitation of the quadrupole electromagnet, and then irradiates the scanning electromagnet 8 again. By repeating this operation, the irradiated object 5 is irradiated in the beam traveling direction and the direction orthogonal thereto.

  The beam dose monitor 9 is used to determine the timing for changing the irradiation position of the charged particle beam on the irradiated object 5, and the beam position monitor 10 is used together with the scanning electromagnet 8 to move the charged particle beam to the correct position. These operations are the same as in the prior art.

Next, reduction of the increase in the beam diameter of the charged particle beam by the quadrupole electromagnet will be described.
As described above, when passing through the variable range shifter 4, the beam diameter of the charged particle beam increases. Similarly, the beam diameter increases when passing through the irradiated object 5, but the beam diameter when the variable range shifter 4 and the irradiated object 5 are not present is σ ₀ , and the increase of the beam diameter by the variable range shifter 4 is σ. _If the increase of the beam diameter by _RS and the irradiated body is _στ , the beam diameter σ in the irradiated body 5 is given by the following equation.

したがって、可変レンジシフター４のアクリル板の厚さや被照射体５における荷電粒子線の飛程が大きくなると、可変レンジシフター４よりビーム進行方向上流の機器で調整可能なσ_０のσへの相対的な寄与は小さくなるため、可変レンジシフター４より上流の機器を用いては被照射体５におけるビーム径を小さくすることはできなくなる。

Accordingly, when the thickness of the acrylic plate of the variable range shifter 4 and the range of the charged particle beam in the irradiated object 5 are increased, the relative _value of σ ₀ to σ that can be adjusted by a device upstream of the variable range shifter 4 in the beam traveling direction. Therefore, the beam diameter in the irradiated object 5 cannot be reduced using equipment upstream from the variable range shifter 4.

  When there is no device that converges the charged particle beam between the variable range shifter 4 and the irradiated object 5, the beam diameter of the irradiated object 5 is the distance from the variable range shifter 4 to the irradiated object 5 and the variable range shifter 4. In order to reduce the increase of σ, it is inevitable that the variable range shifter 4 is brought close to the irradiated object 5 and applied to a treatment apparatus. However, there is a problem that the patient feels intimidating due to the moving sound of the variable range shifter 4.

Therefore, by using the quadrupole magnets 6 disposed between the variable range shifter 4 and the irradiation object 5, to reduce the sigma _RS by focusing the divergence of the charged particle beam due to the scattering in the variable range shifter 4. In this example, four quadrupole electromagnets are used, but other quadrupole electromagnets such as triples may be used.
The amount of excitation of the quadrupole electromagnet 6 is set using the irradiation controller 11 to a value determined by the energy of the charged particle beam supplied from the particle accelerator and the thickness of the variable range shifter 4.

  If this method is used, the beam diameter at the irradiation object 5 can be made smaller than that of the conventional method, and the irradiation object 5 can be irradiated with spatially precise irradiation. In addition, since the variable range shifter 4 can be disposed at a location away from the irradiated object 5, there is no problem of intimidation to the patient in the treatment apparatus, and the variable range shifter 4 is driven at high speed to increase the energy of the charged particle beam at high speed. It can be changed.

  In addition, since the influence of the scattering of the variable range shifter 4 can be reduced, the maximum thickness of the variable range shifter 4 is made larger than that of the conventional method, and the energy change range of the charged particle beam by the range shifter is expanded as compared with the conventional method. It is possible to reduce the number of times of changing the emission energy of the particle accelerator that supplies the charged particle beam.

In addition, as shown in FIG. 2, a ridge filter 12 may be added to widen the Bragg peak so that the expansion Bragg peak (SOBP) can be efficiently formed by the variable range shifter 4. .
According to the present invention, by using the quadrupole electromagnet 6 disposed between the variable range shifter 4 and the irradiated object 5, convergence of the divergence of the charged particle beam due to scattering by the variable range shifter 4 is achieved. As described above, the ridge filter 12 can be disposed upstream of the scanning electromagnet 8 in the beam traveling direction.
By disposing the ridge filter 12 upstream of the scanning electromagnet 8 in the beam traveling direction, the charged particle beam can pass through a predetermined region of the ridge filter, so that it is possible to avoid deterioration of the uniformity of the Bragg peak due to the ridge structure. it can.

  Further, by using a quadrupole electromagnet 6 disposed between the variable range shifter 4 and the irradiated object 5, the charged particle beam emitted by the variable range shifter 4 is converged by converging the divergence of the charged particle beam due to scattering by the variable range shifter 4. Since the increase in the beam diameter of the beam can be reduced, the allowable value for the increase in the beam diameter of the charged particle beam due to scattering by the ridge filter 12 is larger than that of the conventional apparatus, and the range for selecting the height of the ridge of the ridge filter 12 is increased. spread.

Embodiment 2. FIG.
When the acrylic plate is not inserted into the variable range shifter 4, the divergence at the variable range shifter 4 is eliminated. However, when the change in the divergence angle at the variable range shifter 4 is large, the control of the beam diameter becomes complicated. .
As shown in FIG. 3, the particle beam irradiation apparatus and the particle beam therapy apparatus according to the second embodiment are provided with a thin beam scatterer 13 made of a thin film of tungsten or lead, for example, upstream of the variable range shifter 4 in the beam traveling direction. Thus, even when the acrylic plate is not inserted into the variable range shifter 4, the divergence angle of the charged particle beam incident on the quadrupole electromagnet 6 is increased so that the thickness of the acrylic plate of the variable range shifter 4 is changed. The rate of change in the divergence angle due to is relatively small.
By providing the beam scatterer 13, the excitation amount of the quadrupole electromagnet does not change greatly depending on the thickness of the variable range shifter 4, and irradiation control can be facilitated.

Embodiment 3 FIG.
In the first embodiment, in order to reduce the energy of the charged particle beam, the case where only the variable range shifter 4 provided at the position away from the irradiated object 5 upstream in the beam traveling direction is described, but it is shown in FIG. As described above, the fixed range shifter 14 can be provided in the vicinity of the irradiated body 5 so that the energy of the charged particle beam incident on the irradiated body 5 can be lowered also in the beam traveling direction downstream of the quadrupole electromagnet 6. .
When the energy of the charged particle beam is lowered by the variable range shifter 4 to a value that stops near the surface of the irradiated object 5, the momentum width of the charged particle beam that has passed through the variable range shifter 4 becomes very large. The beam convergence force of the quadrupole electromagnet 6 is weakened due to the influence of chromatic aberration, and the beam diameter of the charged particle beam in the irradiated object 5 cannot be reduced.

  Therefore, the variable range shifter 4 upstream of the beam traveling direction of the quadrupole electromagnet 6 adjusts the fluctuation range of the energy decrease of the charged particles. However, the adjustment range weakens the beam convergence force of the quadrupole electromagnet 6 due to the influence of chromatic aberration. On the other hand, the energy of the charged particles is further reduced to a predetermined value by the fixed range shifter 14 on the downstream side of the beam traveling direction of the quadrupole electromagnet 6 while the influence is not exerted. In addition, since the variable range shifter 4 adjusts the fluctuation range of the energy drop of the charged particles during one irradiation unit, the fixed range shifter 14 does not need to change the thickness during irradiation. In the case where the energy reduction width of the charged particles is greatly different in different irradiation units, it is necessary to change the thickness of the fixed range shifter 14.

  In addition to the variable range shifter 4 upstream of the quadrupole electromagnet 6 in the beam traveling direction, the fixed range shifter 14 is disposed in the vicinity of the irradiated object 5 downstream of the quadrupole electromagnet 6 in the beam traveling direction. By limiting the momentum width of the charged particle beam incident on the surface to avoid the problem of chromatic aberration, it is possible to irradiate a charged particle beam having a small beam diameter from the inside of the irradiated object 5 to the vicinity of the surface.

Embodiment 4 FIG.
Instead of providing the fixed range shifter 14 downstream in the beam traveling direction of the quadrupole electromagnet 6 as in the third embodiment, a charged particle beam caused by chromatic aberration of the quadrupole electromagnet 6 by providing a beam slit for reducing the emittance of the charged particle beam. It is also possible to solve the problem of increasing the beam diameter.
FIG. 5 is a diagram showing the configuration of the particle beam irradiation apparatus and the particle beam therapy apparatus according to the fourth embodiment. In contrast to the configuration of FIG. 1, a variable beam slit 15 having a variable aperture diameter is provided with a quadrupole electromagnet 6. In addition, the increase in the divergence angle of the charged particle beam due to scattering by the variable range shifter 4 is controlled. The opening diameter of the variable beam slit 15 is controlled by the irradiation controller 11 depending on the thickness of the variable range shifter 4.

  When the energy of the charged particle beam is lowered by the variable range shifter 4 to a value that stops near the surface of the irradiated object 5, the emittance of the charged particle beam is reduced by the variable beam slit 15, and the quadrupole electromagnet 6. This cancels the increase in the beam diameter of the charged particle beam due to the chromatic aberration. The use of the variable beam slit 15 eliminates the need for the fixed range shifter 14 shown in the third embodiment, thereby further reducing the intimidation of the patient in the treatment apparatus.

  Although the number of charged particles reaching the irradiated object 5 is reduced by the variable beam slit 15, a part of the charged particle beam is removed by the variable beam slit 15 because the number of irradiated particles required is small. Since it is a case where the vicinity of the surface of the irradiation body 5 is irradiated, a decrease in the number of charged particles is not a problem.

BRIEF DESCRIPTION OF THE DRAWINGS It is an equipment arrangement | positioning figure which shows the radiation irradiation apparatus and particle beam therapy apparatus of Embodiment 1 of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is an equipment arrangement | positioning figure which shows the radiation irradiation apparatus and particle beam therapy apparatus of Embodiment 1 of this invention. It is an equipment arrangement | positioning figure which shows the radiation irradiation apparatus and particle beam therapy apparatus of Embodiment 2 of this invention. It is an equipment arrangement | positioning figure which shows the radiation irradiation apparatus and particle beam therapy apparatus of Embodiment 3 of this invention. It is an equipment arrangement | positioning figure which shows the radiation irradiation apparatus and particle beam therapy apparatus of Embodiment 4 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Particle accelerator 2 Beam transport system 3 Radiation irradiation apparatus 4 Variable range shifter 5 Subject to be irradiated 6 4 pole magnet 7 Fixed beam slit 8 Scanning electromagnet 9 Beam dose monitor 10 Beam position monitor 11 Irradiation control apparatus 12 Ridge filter 13 Beam scatterer 14 Fixed range shifter 15 Variable beam slit

Claims (6)

A variable range shifter that reduces the energy of the charged particle beam,
A quadrupole electromagnet in which the amount of excitation is controlled according to the energy of the charged particle beam reduced by the variable range shifter to converge the divergence of the charged particle beam due to scattering by the variable range shifter;
A scanning electromagnet for changing the beam trajectory of the charged particle beam ;
A particle beam irradiation apparatus comprising: a fixed beam slit having a fixed aperture width that is disposed between the variable range shifter and the quadrupole electromagnet and restricts an increase in a divergence angle of the charged particle beam . A variable range shifter that reduces the energy of the charged particle beam,
The amount of excitation is controlled according to the energy of the charged particle beam lowered by the variable range shifter.
A quadrupole that converges the divergence of the charged particle beam due to scattering by the variable range shifter
An electromagnet,
A scanning electromagnet for changing the beam trajectory of the charged particle beam;
A particle beam irradiation apparatus comprising: a ridge filter that is disposed between the quadrupole electromagnet and the scanning electromagnet and that widens a Bragg peak . A variable range shifter that reduces the energy of the charged particle beam,
The amount of excitation is controlled according to the energy of the charged particle beam lowered by the variable range shifter.
A quadrupole that converges the divergence of the charged particle beam due to scattering by the variable range shifter
An electromagnet,
A scanning electromagnet for changing the beam trajectory of the charged particle beam;
A particle beam irradiation apparatus , comprising: a beam scatterer disposed upstream of the quadrupole electromagnet in the beam traveling direction and increasing a divergence angle of the charged particle beam . A variable range shifter that reduces the energy of the charged particle beam,
The amount of excitation is controlled according to the energy of the charged particle beam lowered by the variable range shifter.
A quadrupole that converges the divergence of the charged particle beam due to scattering by the variable range shifter
An electromagnet,
A scanning electromagnet for changing the beam trajectory of the charged particle beam;
A particle beam irradiation apparatus , comprising: a fixed range shifter disposed downstream of the quadrupole electromagnet in a beam traveling direction and reducing energy of the charged particle beam. A variable range shifter that reduces the energy of the charged particle beam,
The amount of excitation is controlled according to the energy of the charged particle beam lowered by the variable range shifter.
A quadrupole that converges the divergence of the charged particle beam due to scattering by the variable range shifter
An electromagnet,
A scanning electromagnet for changing the beam trajectory of the charged particle beam;
A variable is disposed between the variable range shifter and the quadrupole electromagnet, and the aperture width changes according to the energy of the charged particle beam changed by the variable range shifter, thereby limiting the beam width of the charged particle beam. A particle beam irradiation apparatus comprising a beam slit . A particle accelerator for generating a charged particle beam and a beam transport for transporting the charged particle beam to an irradiation chamber;
A particle beam therapy system comprising a delivery system and the particle beam irradiation apparatus according to any one of claims 1 to 5.

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