1. Field of the Invention
The present invention relates to particle-beam exposure apparatuses exposing, into targets to be exposed, charged particle beams supplied by particle accelerators, and to particle-beam therapeutic apparatuses using the particle-beam exposure apparatuses.
2. Description of the Related Art
In a conventional particle-beam exposure apparatus using a range shifter for varying a range of a charged particle beam inside a target to be exposed, in order to reduce the variation, due to scattering in the range shifter, of the charged-particle-beam diameter, the range shifter has been placed close to the target, and a scatter device as beam scatterer as well as a set of quadrupole magnets has also been placed at the upstream side of the range shifter along the beam traveling direction (for example, referring to Patent Document 1), or a beam collimator has been placed (for example, referring to Patent Document 2).
[Patent Document 1] Japanese Laid-Open Patent Publication 212,253/2001 (Paragraph 0053, FIG. 1).
[Patent Document 2] Japanese Laid-Open Patent Publication 562/2001 (Paragraph 0025, FIG. 7).
Because the conventional particle-beam exposure apparatus is configured as above, the range shifter has had to be placed close to the target; therefore, in a case of a therapeutic apparatus using the particle-beam exposure apparatus for exposing the particle beam to the head and neck portion of a patient, because of the spatial interference with the shoulder of the patient, the range shifter cannot be drawn to the portion to be exposed, and consequently, a problem has occurred in which the charged-particle-beam diameter cannot be narrowed to a needed size. Moreover, because the range shifter whose thickness is needed to be changed during treatment has been placed dose to the patient, especially when high-speed driving of the range shifter is performed, a problem has occurred in which the patient feels intimidated by a movement noise. Furthermore, because the beam diameter at the target is almost determined by contribution of scattering in the range shifter and the target, the beam diameter cannot be narrowed by the set of quadrupole magnets or the beam collimator placed at the upstream side of the range shifter along the beam traveling direction; consequently, in the conventional apparatus, only controlling towards the direction in which the beam diameter is widened has been possible.
An objective of the present invention, which is made to solve the above described problems, is to obtain a particle-beam exposure apparatus and a particle-beam therapeutic apparatus, in which, by reducing diameter increase, due to scattering in a range shifter, of a charged particle beam, the charged particle beam whose diameter is so narrow that spatially accurate exposure into the target is possible can be supplied, as well as, by placing the range shifter at a position apart from a patient, intimidation caused by a movement noise, etc. can be prevented.
A particle-beam exposure apparatus and a particle-beam therapeutic apparatus include a range shifter for varying energy of a charged particle beam with a thickness of the range shifter being changed during exposure of the charged particle beam, so that a range of the charged, particle beam at a target to be exposed is set to a desired value; and a set of quadrupole magnets, being placed between the range shifter and the target, based on the magnetization amount of the set of quadrupole magnets being controlled corresponding to the charged-particle-beam energy varied by the range shifter, for reducing diameter increase, due to scattering at the range shifter, of the charged particle beam at the target.
According to this method, the beam diameter at the target can be set to a smaller value than that in the conventional method, and spatially accurate exposure into the target can be realized; moreover, the range shifter can be placed at a position apart from the target.
Hereinafter, a particle-beam exposure apparatus, and a particle-beam therapeutic apparatus composed of this particle-beam exposure apparatus, a particle accelerator, and a beam transport system, according to Embodiment 1 of the present invention, are explained based on
Next, an operation of the particle-beam exposure apparatus is explained. The charged particle beam introduced to the variable-type range shifter 4 from the particle accelerator 1 through the beam transport system 2 passes through the acrylic board included in the variable-type range shifter 4; thereby, the beam energy is decreased. The variable-type range shifter 4 is configured, for example, by a plurality of acrylic boards whose thicknesses are differed from each other so that the combination of these acrylic boards can be changed, or by a wedge-shaped acrylic board so that the position where the charged particle beam passes can be changed; thereby, the thickness of the acrylic board through which the charged particle beam passes can be changed, and consequently, it can be controlled how much the particle-beam energy is decreased.
On the other hand, due to the scattering in the variable-type range shifter 4, the beam diameter of the charged particle beam is increased. The fixed-type beam slit 7 limits the divergence angle of the charged particle beam due to the scattering in the variable-type range shifter 4. Because charged particles whose divergence angles are relatively large are removed by the fixed-type beam slit 7, radio activation of the units placed at the downstream side of the fixed-type beam slit 7 along the beam traveling direction is prevented.
Moreover, exposure into the target 5 placed along an orientation perpendicular to the beam traveling direction is performed by keeping the thickness of the variable-type range shifter 4 and the magnetization amount of the set of quadrupole magnets 6 to be constant, and changing the charged-particle-beam route using the scanning electromagnets 8. When once the exposure to the orientation perpendicular to the beam traveling direction has been completed, after the thickness of the variable-type range shifter 4 and the magnetization of the set of quadrupole magnets are changed by the exposure controller 11, exposure using the scanning electromagnets 8 is performed again. By repeating this operation, exposure is performed into the target 5 along the beam traveling direction and along the orientation perpendicular to this direction.
The beam dose monitor 9 is used for determining the timing of changing the charged-particle-beam exposing position on the target 5; meanwhile, the beam position monitor 10 is used for moving the charged particle beam to the correct position, which is used together with the scanning electromagnets 8. These operations are similar to those in the conventional technology.
Next, the reducing of the increase of the charged-particle-beam diameter by using the set of quadrupole magnets is explained. As described above, when the charged particle beam passes through the variable-type range shifter 4, the beam diameter of the charged particle beam increases. When the charged particle beam passes through the target 5, the beam diameter also increases similarly; therefore, given that the beam diameter is σ0 when the variable-type range shifter 4 and the target 5 are not placed, the increase of the beam diameter due to the variable-type range shifter 4 is σRS, and the increase of the beam diameter due to the target is στ, the beam diameter σ at the target 5 is given by the following equation.
σ2=σ02+σRS2+στ2 [Eg. 1.]
Therefore, when the thickness of the acrylic board included in the variable-type range shifter 4 or the range of the charged particle beam at the target 5 increases, relative contribution of σ0, which is adjustable using a unit placed at the upstream side of the variable-type range shifter 4 along the beam traveling direction, to σ decreases; therefore, the beam diameter at the target 5 cannot be decreased using the unit placed at the upstream side of the variable-type range shifter 4.
Because when a device for focusing the charged particle beam is not provided between the variable-type range shifter 4 and the target 5, the beam diameter at the target 5 increases in proportional to the product of the distance from the variable-type range shifter 4 to the target 5 and the divergence angle due to the scattering in the variable-type range shifter 4, in order to reduce the increase of σ, it is unavoidable to draw the variable-type range shifter 4 dose to the target 5; therefore, when the apparatus is applied to a therapeutic apparatus, a problem occurs, for example, in which a patient feels intimidated by a movement noise from the variable-type range shifter 4.
Therefore, by using the set of quadrupole magnets 6 placed between the variable-type range shifter 4 and the target 5, σRS is decreased by focusing the divergence of the charged particle beam due to the scattering in the variable-type range shifter 4. Although, in this example, a quartet set of quadrupole magnets is used as the set of quadrupole magnets, a triplet set of quadrupole magnets, for example, may be used. Here, using the exposure controller 11, the magnetization amount of the set of quadrupole magnets 6 is set to a value determined by the charged-particle-beam energy supplied from the particle accelerator and the thickness of the variable-type range shifter 4.
By using this method, the beam diameter at the target 5 can be set to a smaller value than that in the conventional method, and spatially accurate exposure to the target can be realized. Moreover, because the variable-type range shifter 4 can be placed at a position apart from the target 5, the problem of the intimidation to the patient by the therapeutic apparatus does not occur; therefore, by high-speed driving of the variable-type range shifter 4, the charged-particle-beam energy can be varied high-speedily.
Because scattering effect of the variable-type range shifter 4 can be surely prevented, by setting the maximum thickness of the variable-type range shifter 4 thicker than that in the conventional method, the energy variable range of the charged particle beam using the range shifter can be more extended, than that in the conventional method; thereby, the number of operations for changing the energy outputted from the particle accelerator that supplies the charged particle beam can be reduced.
Moreover, as represented in
Furthermore, by using the set of quadrupole magnets 6 placed between the variable-type range shifter 4 and the target 5, and by focusing the divergence of the charged particle beam due to the scattering in the variable-type range shifter 4, the increase of the charged-particle-beam diameter in the variable-type range shifter 4 can be reduced; thereby, an allowable value in response to the increase of the charged-particle-beam diameter due to the scattering in the ridge filter 12 becomes larger than that in the conventional apparatus, and the range where the ridge height of the ridge filter 12 is selected extends.
If the acrylic board is not inserted into the variable-type range shifter 4, the divergence at the variable-type range shifter 4 is prevented; however, thus, when the varying of the divergence angle at the variable-type range shifter 4 is widened, the beam-diameter control becomes complicated. In a particle-beam exposure apparatus and a particle-beam therapeutic apparatus according to Embodiment 2, as represented in
In Embodiment 1, in order to decrease the charged-particle-beam energy, the case in which only the variable-type range shifter 4 provided at the upstream side apart from the target 5 along the beam traveling direction is used has been explained; however, as represented in
Therefore, varying width of the charged-particle-beam energy is regulated by the variable-type range shifter 4 placed at the upstream side of the set of quadrupole magnets 6 along the beam traveling direction, where the regulating width is set at a range in which affection that the beam focusability by the set of quadrupole magnets 6 is decreased due to the chromatic aberration does not occur, and, on the other hand, the charged-particle-beam energy is also decreased to a predetermined value by the fixed-type range shifter 14 placed at the downstream side of the set of quadrupole magnets 6 along the beam traveling direction. Here, because the varying width of the decrease of the charged-particle-beam energy is regulated by the variable-type range shifter 4 during an exposure unit, regarding the fixed-type range shifter 14, the thickness is needless to be changed during the exposure. Regarding different exposure units, when the decreasing widths of the charged-particle-beam energy are significantly differed from each other, the thickness of the fixed-type range shifter 14 becomes necessary to be changed.
According to the configuration in which, in addition to the variable-type range shifter 4 placed at the upstream side of the set of quadrupole magnets 6 along the beam traveling direction, the fixed-type range shifter 14 is placed close to the target 5 that is placed, at the downstream side of the set of quadrupole magnets 6 along the beam traveling direction, the momentum width of the charged particle beam being incident onto the set of quadrupole magnets 6 is limited, and the problem of the chromatic aberration is prevented; thereby, the charged particle beam having relatively narrow beam diameter can be exposed from the inside to the surface proximity of the target 5.
By providing a beam slit for reducing the charged-particle-beam emittance instead, of providing the fixed-type range shifter 14 at the downstream side of the set of quadrupole magnets 6 along the beam traveling direction as described in, Embodiment 3, the problem can also be solved in which the charged-particle-beam diameter increases due to the chromatic aberration at the set of quadrupole magnets 6.
When the charged-particle-beam energy is decreased using the variable-type range shifter 4 into a value where the beam is stopped at the surface proximity of the target 5, the charged-particle-beam emittance is reduced by the variable-type beam slit 15, so that the increase of the charged-particle-beam diameter due to the chromatic aberration at the set of quadrupole magnets 6 is cancelled out. Because the fixed-type range shifter 14 described in Embodiment 3 becomes unnecessary by using the variable-type beam slit 15, intimidation that a patient feels can be further reduced in the therapeutic apparatus.
Here, the number of the charged particles reaching the target 5 decreases by the variable-type beam slit 15; however, because, only when the charged particle beam exposes the surface proximity of the target 5 where the number of the exposing particles required is relatively small, a part of the charged particle beam is removed by the variable-type beam slit 15, it is not a problem that the number of the charged particles decreases.
Number | Date | Country | Kind |
---|---|---|---|
2006-007364 | Jan 2006 | JP | national |
Number | Name | Date | Kind |
---|---|---|---|
5111173 | Matsuda et al. | May 1992 | A |
5260581 | Lesyna et al. | Nov 1993 | A |
5363008 | Hiramoto et al. | Nov 1994 | A |
5789875 | Hiramoto et al. | Aug 1998 | A |
5969367 | Hiramoto et al. | Oct 1999 | A |
6218675 | Akiyama et al. | Apr 2001 | B1 |
6316776 | Hiramoto et al. | Nov 2001 | B1 |
6424084 | Kimiya et al. | Jul 2002 | B1 |
6479926 | Awano et al. | Nov 2002 | B1 |
6597096 | Amano et al. | Jul 2003 | B1 |
6814694 | Pedroni | Nov 2004 | B1 |
6859741 | Haberer et al. | Feb 2005 | B2 |
7122978 | Nakanishi et al. | Oct 2006 | B2 |
7154107 | Yanagisawa et al. | Dec 2006 | B2 |
7326942 | Shichi et al. | Feb 2008 | B2 |
7449701 | Fujimaki et al. | Nov 2008 | B2 |
20040000650 | Yanagisawa et al. | Jan 2004 | A1 |
20040056212 | Yanagisawa et al. | Mar 2004 | A1 |
20040149934 | Yanagisawa et al. | Aug 2004 | A1 |
20040162457 | Maggiore et al. | Aug 2004 | A1 |
20040200983 | Fujimaki et al. | Oct 2004 | A1 |
20050231138 | Nakanishi et al. | Oct 2005 | A1 |
20060065854 | Shichi et al. | Mar 2006 | A1 |
20100213384 | Furukawa et al. | Aug 2010 | A1 |
Number | Date | Country |
---|---|---|
11-197258 | Jul 1999 | JP |
2001-000562 | Jan 2001 | JP |
2001-061978 | Mar 2001 | JP |
2001-212253 | Aug 2001 | JP |
2002-189004 | Jul 2002 | JP |
2004-069683 | Mar 2004 | JP |
2004-144538 | May 2004 | JP |
2004-192931 | Jul 2004 | JP |
2004-321830 | Nov 2004 | JP |
Number | Date | Country | |
---|---|---|---|
20090032721 A1 | Feb 2009 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 11480430 | Jul 2006 | US |
Child | 12244356 | US |