JP3964769B2 - Medical charged particle irradiation equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a medical charged particle beam irradiation apparatus that irradiates a charged particle beam to an irradiation target, and in particular, a medical charged particle irradiation apparatus that expands an irradiation range by scanning a beam using a plurality of scanning electromagnets. About.
[0002]
[Prior art]
Medical charged particle irradiation equipment that treats cancer, tumors, etc. by irradiating a patient's affected part with a charged particle beam such as protons or carbon ions is used to generate charged particles generated by an ion source and accelerated by an accelerator such as a synchrotron. Then, after the irradiation field is formed by the irradiation field forming means in accordance with the shape of the affected part, the affected part of the patient lying on the patient bed is irradiated (for example, see Non-Patent Document 1).
[0003]
The irradiation field forming means adjusts the dose distribution by forming the irradiation field of the charged particle beam according to the three-dimensional shape of the irradiation target (affected part), and the traveling direction of the charged particle beam (the depth direction of the irradiation target). , The Z axis), a lateral beam forming unit for shaping an irradiation range in a plane perpendicular to the Z axis (XY plane having the X axis and the Y axis), and an irradiation range in the traveling direction of the charged particle beam (Z axis) It is comprised from the range adjustment part which forms.
[0004]
The range adjustment unit adjusts the energy of the charged particle beam according to the depth of the irradiation target, and applies the charged particle beam to the shape of the irradiation target in the traveling direction (depth direction) of the charged particle beam. It is something to be shaped.
[0005]
The transverse beam forming unit expands the charged particle beam in a plane (XY plane) direction perpendicular to the traveling direction of the charged particle beam, and then cuts the expanded charged particle beam with a collimator to charge the charged particle beam. The charged particle beam is shaped according to the shape of the irradiation target on a plane perpendicular to the traveling direction of the particle beam. The beam expansion at this time includes a method of scanning the beam, a method of expanding the beam diameter, or a method of combining them.
[0006]
In the method of scanning a beam, in general, the two beam deflecting means are often arranged so that their deflecting surfaces are perpendicular to each other. Particularly, in the irradiation of a high energy beam such as a proton or heavy particle, the beam An electromagnet (scanning electromagnet) is often used as the deflecting means. For example, an X-direction scanning electromagnet that has a magnetic pole surface perpendicular to the Y direction and generates a magnetic field in the Y direction and deflects the beam in the X direction is disposed on the upstream side, and a magnetic pole surface perpendicular to the X direction is provided. A Y-direction scanning electromagnet that generates and deflects the beam in the Y-direction is disposed downstream. In this case, the X-direction position of the beam is gradually deflected in the upstream X-direction scanning electromagnet and changes linearly after passing through the electromagnet, so that the X-direction scanning point is near the center of the upstream X-direction scanning electromagnet. Thus, the Y-direction scanning point of the beam is approximately near the center of the downstream Y-direction scanning magnet.
[0007]
In such a configuration, in the downstream Y-direction scanning electromagnet, the beam scanning range by the upstream X-direction scanning magnet increases the beam passage range in the X-direction compared to the upstream side, and as a result, the X-direction that is the magnetic field generation direction. It is necessary to increase the magnetic pole spacing at. Here, in the scanning electromagnet, since the magnetic resistance increases as the magnetic pole interval in the magnetic field generation direction increases, the power consumption increases in proportion to the power of the magnetic pole interval (for example, the square). For this reason, the power consumption in the Y-direction scanning electromagnet is remarkably increased due to the increase in the magnetic pole spacing in the X direction as described above, and the operating cost (running cost) is increased. In addition, for the power source for exciting the scanning electromagnet, the power source capacity represented by the product of the maximum voltage and the maximum current is usually increased in proportion to the magnetic pole generation in the magnetic field generation direction, for example. In the configuration as described above, it is necessary to prepare a very large power source capacity as an excitation power source for the Y-direction scanning electromagnet, which increases the equipment cost (initial cost).
[0008]
Accordingly, conventionally, the X-direction scanning electromagnet and the Y-direction scanning electromagnet are arranged at a large distance, and the deflection electromagnet and the quadrupole electromagnet provided between these two scanning electromagnets in the X-direction. An apparatus that uses a convergence function to reduce the beam passage range in the X direction in the vicinity of the downstream Y-direction scanning magnet has been proposed (see, for example, Patent Document 1).
[0009]
In this prior art, the X-direction scanning electromagnet deflects the beam in the X direction and deflects it so as to shift the position, and then uses the beam converging function of the deflecting electromagnet or quadrupole electromagnet to pass the beam in the X direction while passing through it. The beam is gradually deflected so as to reduce the positional deviation, and once focused in the vicinity of the downstream Y-direction scanning electromagnet. Thereby, the beam scanning point is substantially moved to the focal position (in other words, in the vicinity of the Y-direction scanning electromagnet), and the beam passing range in the X direction by the downstream Y-direction scanning electromagnet is reduced. Then, after the focal point, the particle beam which has passed through the Y-direction scanning electromagnet and whose beam passing range is increased again in the X direction is introduced into the collimator.
[0010]
[Non-Patent Document 1]
“Review of Scientific Instruments Vol.64 No.8 (August 1993)” (p. 2055-2122)
[Patent Document 1]
Japanese Patent Laid-Open No. 10-282300 (paragraph numbers [0011], [0012] and FIG. 7)
[Problems to be solved by the invention]
In the above prior art, by using the X-direction beam converging function of the deflection electromagnet and the quadrupole electromagnet provided between the X-direction scanning electromagnet and the Y-direction scanning electromagnet, the focus is once set near the downstream Y-direction scanning electromagnet. The beam passing range in the direction scanning electromagnet is reduced. As a result, an increase in power consumption and an increase in excitation power source capacity due to an increase in the magnetic pole spacing in the X direction in the Y direction scanning electromagnet can be prevented, and the cost can be reduced.
[0013]
However, since the beam converging function of the deflecting electromagnet or the quadrupole electromagnet is not so large, the charged particle beam which has been deflected so that the beam is once deflected by the X-direction scanning electromagnet is shifted in reverse. While the beam is deflected so as to be reduced, the maximum value of the beam passing range in the X direction becomes relatively large along with the size of the transport distance, and accordingly, the beam passing range in the X direction by these deflecting magnets and quadrupole electromagnets is increased. Become. That is, although the scanning electromagnet can be reduced in size, the other beam deflection means (in this example, a quadrupole electromagnet or a large-sized deflection electromagnet) is increased in the X direction. For this reason, the deflection of the support structure increases due to an increase in their own weight (particularly, the tendency becomes remarkable in the rotating gantry as in this known example), and as a result, it is difficult to improve the beam irradiation accuracy.
[0014]
An object of the present invention is to provide a charged particle irradiation apparatus for medical use capable of reducing the cost without increasing the size of other beam deflecting means.
[0015]
[Means for Solving the Problems]
(1) In order to achieve the above object, the present invention provides a charged particle beam irradiation apparatus for medical use that irradiates an affected part of a patient with charged particles. An incident charged particle beam is irradiated in a plane perpendicular to the beam traveling direction. A first scanning electromagnet that bends the beam in one direction to deflect the beam, and a charged particle beam that is provided downstream of the first scanning electromagnet and is deflected by the first scanning electromagnet, Contrary to the deflection by the first scanning electromagnet Small deviation of the beam position And focus on the downstream side like To the one direction A second scanning electromagnet that deflects, and a second scanning electromagnet provided downstream from the second scanning electromagnet, To the one direction Deflected The passing range in the one direction is reduced And a third scanning electromagnet that deflects the charged particle beam in a direction perpendicular to the one direction in a plane perpendicular to the beam traveling direction.
[0016]
In the present invention, for example, the first scanning electromagnet deflects the beam so that the position is shifted by bending the beam in the X direction, for example, and then the second scanning electromagnet on the downstream side deflects the beam in the X direction so as to reduce the displacement. Thus, for example, it is possible to focus once in the vicinity of the third Y-direction scanning electromagnet further downstream. Thereby, the beam scanning point is substantially moved to the focal position (in other words, in the vicinity of the third scanning electromagnet), the beam passing range in the X direction in the downstream third scanning electromagnet is reduced, and the third scanning electromagnet after the focal point. Then, the beam passing range is expanded again in the X direction and the particle beam having a predetermined size is introduced into the collimator.
[0017]
At this time, the beam passing range is drastically reduced in the X direction by using a second scanning electromagnet having a high beam deflection function without using a deflection electromagnet or a quadrupole electromagnet which is not so large as in the conventional structure. Therefore, once the beam is bent by the first scanning magnet and the position is shifted, the transport distance can be reduced while the beam position deviation is reduced, and the maximum value of the beam passing range at that time can be reduced. Can do. Therefore, it is possible to reduce the size of other beam deflecting means such as a deflection electromagnet or a quadrupole electromagnet normally provided between them.
[0018]
On the other hand, at this time, in the present invention, the first scanning electromagnet (X direction), the second scanning electromagnet (X direction), the third scanning electromagnet, for example, from the original two in total, for example, one X direction scanning electromagnet and Y direction scanning electromagnet. Since the number of scanning electromagnets (in the Y direction) is increased by one, the power consumption and the power supply capacity corresponding to that increase are added separately.
[0019]
However, regarding power consumption, for example, in the above-described original structure in which one X-direction scanning electromagnet and one Y-direction scanning electromagnet are arranged, the downstream Y-direction scanning electromagnet responds to an increase in the X-direction beam passage range. The magnetic pole spacing in the X direction, which is the magnetic field generation direction, is large. As described above, since the power consumption is proportional to, for example, the square of the magnetic pole interval in the magnetic field generation direction, the power consumption of the Y-direction scanning magnet reaches, for example, about five times that of the X-direction scanning magnet. For this reason, the total power consumption of the X direction scanning electromagnet and the Y direction scanning electromagnet increases significantly.
[0020]
In the present invention, since the magnetic pole interval can be reduced to, for example, about 1/2 of the original structure by reducing the X-direction beam passing range in the third scanning electromagnet on the most downstream side as described above, the original Y-direction scanning is performed. The power consumption of the third scanning electromagnet can be reduced to about 1/3 of the electromagnet. On the other hand, since the first scanning electromagnet as a new addition has a small deflection amount and is extremely small, it is sufficient to perform the original X-direction scanning even if the power consumption of the first and second scanning electromagnets is totaled. It does not reach twice the power consumption of electromagnets. As a result, the total power consumption of the three first to third scanning electromagnets can be reduced to, for example, about ½ the total power consumption of the original two X-direction and Y-direction scanning electromagnets. Cost) can be reduced.
[0021]
Further, regarding the power source capacity, in the above-described original structure in which one X-direction scanning electromagnet and one Y-direction scanning electromagnet are arranged, the power source capacity is proportional to the magnetic pole interval in the magnetic field generation direction as described above. Therefore, the power supply capacity necessary for the excitation power source for the Y-direction scanning magnet reaches, for example, several times (3 to 5 times) the excitation power source for the X-direction scanning magnet. For this reason, a particularly large power source is required for the Y-direction scanning electromagnet, and in some cases, it is not available in the normal market and needs to be manufactured separately, which increases the equipment cost (initial cost).
[0022]
In the present invention, as described above, the magnetic pole spacing is reduced by reducing the X direction beam passing range in the third scanning electromagnet on the most downstream side, so that the third is about 60% of the original Y direction scanning electromagnet. The power supply capacity of the excitation power source for the scanning electromagnet can be reduced, and the cost can be significantly reduced. On the other hand, since the first scanning electromagnet, which is a new addition, has a small deflection amount and is extremely small, the power capacity used for the first scanning electromagnet is the power supply of the original X-direction scanning electromagnet. The capacity of about 1/3 of the capacity is sufficient, and the power capacity used for the second scanning electromagnet is sufficient so as not to be much different from the original X-direction scanning electromagnet. As a result, overall, the equipment cost (initial cost) required for the excitation power source for the three first to third scanning magnets can be reduced to the original excitation power source for the two X and Y direction scanning magnets. It can be at least approximately equal or smaller than the required equipment cost.
[0023]
As described above, in the present invention, the cost can be reduced without increasing the size of the other beam deflecting means.
[0024]
(2) In order to achieve the above object, the present invention is also directed to a medical charged particle irradiation apparatus that irradiates an affected part of a patient with charged particles, and the incident charged particle beam is irradiated in a plane perpendicular to the beam traveling direction. A first scanning electromagnet that bends the beam in one direction to deflect the beam, and a charged particle beam that is provided downstream from the first scanning electromagnet and is deflected by the first scanning electromagnet, Contrary to the deflection by the first scanning electromagnet Small deviation of the beam position And focus on the downstream side like To the one direction A second scanning electromagnet that deflects, and a second scanning electromagnet provided downstream from the second scanning electromagnet, To the one direction Deflected The passing range in the one direction is reduced A third scanning electromagnet that deflects the charged particle beam in a direction perpendicular to the one direction in a plane perpendicular to the beam traveling direction, a deflection amount by the first scanning electromagnet, and the second scanning electromagnet Deflection amount by The Proportional relationship In First deflection control means for controlling the first and second scanning electromagnets to maintain the first and second scanning electromagnets.
[0025]
By maintaining a proportional relationship between the amount of deflection by the first scanning electromagnet and the amount of deflection by the second scanning electromagnet, the beam bends to increase the misalignment → the misalignment is reduced → the focal point near the third scanning electromagnet. Scanning can be performed easily and reliably while maintaining the behavior.
[0026]
(3) In the above (1) or (2), preferably, a scatterer that scatters a charged particle beam is provided downstream of the third scanning magnet.
[0027]
When a scatterer is provided, the greater the distance from the beam scanning point to the scatterer, the higher the possibility that various beams will enter the scatterer from a wider range in more directions. As a result of the ambiguity of the beam outline, the spread of the angular distribution of the irradiation beam becomes large, and the dose distribution within the irradiation target after the beam is cut out by the collimator (penumbra) becomes large, making it difficult to improve the irradiation accuracy.
[0028]
In the present invention, as described in (1) above, the beam scanning point is substantially moved to the vicinity of the third scanning electromagnet that is the focal position, so by providing a scatterer downstream from the third scanning electromagnet, The distance between the scanning point and the scatterer can be reduced. This can reduce the penumbra of the intra-irradiation dose distribution and improve the irradiation accuracy. In addition, an irradiation apparatus that scans a large area and irradiates a wide area can be realized. In particular, when the beam scanning point is set near the scatterer, the penumbra of the intra-irradiation dose distribution can be further reduced, and the irradiation accuracy can be further improved.
[0029]
(4) In the above (1) or (2), and preferably, a scatterer that scatters a charged particle beam is provided downstream from the second scanning electromagnet and upstream from the third scanning electromagnet.
[0030]
By disposing the scatterer upstream of the third scanning electromagnet in the Y direction, the distance between the scatterer and the irradiation surface is increased, and the amount of scattering necessary to form the same beam intensity distribution on the irradiation surface is reduced. be able to. Thereby, the thickness of a scatterer can be made thin and the energy loss of the beam in a scatterer can be made small. As a result, the energy of the beam that reaches the irradiation surface increases, so that the arrival depth of the beam within the irradiation target becomes deep, and irradiation can be performed on a deeper target.
[0031]
(5) In the above (2), preferably, the first deflection control means includes a single excitation power source common to the first scanning electromagnet and the second scanning electromagnet, and the first scanning electromagnet and the second scanning electromagnet. In the scanning electromagnet, each excitation coil is connected in series to the single excitation power source.
[0032]
Thereby, the beam deflection amounts by the first scanning electromagnet and the second scanning electromagnet can be easily made proportional without any particular adjustment. Therefore, the operation is simplified and the possibility of erroneous irradiation due to deviation can be reduced.
[0033]
(6) In the above (2), preferably, the first deflection control means includes a first excitation power source and a second excitation power source that supply power to the first scanning magnet and the second scanning magnet, respectively. Power supply control means common to the first and second excitation power supplies is provided.
[0034]
In the present invention, the excitation power supplies for the first scanning electromagnet and the second scanning electromagnet are separately provided, so that each excitation current is adjusted by changing the amplification factor, thereby adjusting the scanning point position as desired. can do. Therefore, even when there is a change in the conditions of the equipment between the first scanning electromagnet and the second scanning electromagnet, or when there is a magnet design error, the scanning point can be adjusted so as not to shift, and the third scanning electromagnet of the beam It is possible to avoid collision with the magnetic pole and maintain irradiation accuracy. At this time, since the first and second excitation power sources are controlled by a single signal source called the second power source control means, it is not necessary to adjust the phase of the first and second scanning magnets, and the operation can be performed. In addition to simplification, the possibility of erroneous irradiation due to phase shift can be reduced.
[0037]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0038]
The charged particle irradiation apparatus for medical use of this embodiment is applied to a radiation therapy apparatus known as this type, for example, a proton beam therapy apparatus. Although detailed illustration is omitted, in this proton beam treatment apparatus, a charged particle (for example, proton) beam generated by an injector is transported at a low energy beam as in, for example, the one described in Japanese Patent Laid-Open No. 2001-353228. After passing through the apparatus, it is incident on a synchrotron which is a main accelerator, and is accelerated to the energy required for treatment (usually 100 to 200 MeV) by this synchrotron. The charged particle beam emitted from the synchrotron is incident on the charged particle irradiation apparatus (rotation irradiation apparatus) of the present embodiment.
[0039]
FIG. 2 is a conceptual side view showing the overall schematic structure of the charged particle irradiation apparatus according to the present embodiment. Hereinafter, the traveling direction of the charged particle beam (the depth direction of the irradiation target) is the Z-axis direction (Z direction), and one direction in a plane perpendicular to this is the X direction (in FIG. 2). In the part of the emission nozzle 5 (described later) The direction perpendicular to the X direction in the plane is the Y direction (in FIG. 2). In the part of the emission nozzle 5 (described later) The direction perpendicular to the paper surface).
[0040]
In FIG. 2, the charged particle irradiation apparatus 1 of the present embodiment includes a deflection electromagnet 2A, 2B, 2C for beam transportation, a quadrupole electromagnet 3A, 3B, 3C for beam convergence, a vacuum particle chamber 4, an exit nozzle 5, and A rotating gantry 6 to which an X-direction scanning electromagnet (first scanning electromagnet) 101 is attached and a motor (not shown) for rotating the rotating gantry 6 around a predetermined rotation axis k are provided. By rotating the rotating gantry 6 about the rotation axis k, the irradiation direction can be changed.
[0041]
The exit nozzle 5 is disposed on the X-direction scanning electromagnet (second scanning electromagnet) 102, the Y-direction scanning electromagnet (third scanning electromagnet) 103 disposed on the downstream side thereof, and further on the downstream side thereof. And a scatterer unit (scatterer) 104 that can change the thickness of the scatterer according to conditions.
[0042]
The X-direction scanning electromagnet 102 generates a magnetic field in the Y direction together with the X-direction scanning electromagnet 101 provided outside the emission nozzle 5, and emits a beam in the same plane as the above-described deflection electromagnets 2A, 2B, 2C (with the amount of deflection). (Variably) deflect. At this time, the X-direction scanning electromagnet 101 is deflected so as to shift the position by bending the beam, and the X-direction scanning electromagnet 102 is deflected so as to reduce the deviation of the beam position caused by the X-direction scanning electromagnet 101. These X direction scanning electromagnets 10 1 , 10 2 These excitation coils (not shown) are connected in series to a common X-direction scanning electromagnet power source 105 via power supply lines 106 a and 106 b, and are excited by electric power from the X-direction scanning electromagnet power source 105.
[0043]
The Y direction scanning electromagnet 103 generates a magnetic field in the X direction and deflects the beam in the Y direction (variable amount of deflection). An excitation coil (not shown) of the Y-direction scanning electromagnet 103 is connected to a Y-direction scanning electromagnet power source 107 via a power line 108 and is excited by electric power from the Y-direction scanning electromagnet power source 107.
[0044]
Next, operation | movement of the charged particle irradiation apparatus 1 of this embodiment of the said structure is demonstrated.
[0045]
The beam input to the charged particle irradiation device 1 is transported to the downstream side after the trajectory is bent by the deflecting electromagnets 2 </ b> A to 2 </ b> C and the betatron oscillation is adjusted by the quadrupole electromagnets 3 </ b> A to 3 </ b> C. After exiting from the vacuum chamber 4 through the vacuum window into the air, and passing through the air while being molded by each device in the emission nozzle 5, the irradiation target P is irradiated.
[0046]
In such a beam transport process, the beam passes between the magnetic poles of the X-direction scanning electromagnets 101 and 102, thereby deflecting the electromagnet. 2C Is deflected in the X direction within the same plane, and further the Y direction scanning electromagnet 103 Is deflected in the Y direction by passing between the magnetic poles.
[0047]
FIG. 3 is a diagram illustrating an example of a temporal change in excitation current supplied to the X-direction scanning electromagnets 101 and 102 and the Y-direction scanning electromagnet 103 by the X-direction scanning electromagnet power source 105 and the Y-direction scanning electromagnet power source 107 described above. 4 is a diagram illustrating an example of a temporal change in the amount of movement of the beam center axis on the irradiation surface due to beam deflection by the three scanning electromagnets 101, 102, and 103. FIG.
[0048]
In FIG. 3, in this example, the X-direction scanning electromagnet power source 105 and the Y-direction scanning electromagnet power source 107 generate excitation currents such that their temporal changes are sinusoidal, respectively, in the X-direction scanning electromagnets 101 and 102 and the Y-direction scanning electromagnet 103. The X direction excitation current and the Y direction excitation current are 90 ° out of phase with each other.
[0049]
The central axis of the beam on the irradiation surface moves in the X direction by an amount proportional to the deflection amount of the X direction scanning electromagnets 101 and 102, and moves in the Y direction by an amount proportional to the deflection amount by the Y direction scanning electromagnet 103. As a result, as shown in FIG. 4, the sum of the beam center axis movement amount by the X direction scanning electromagnet 101 and the beam center axis movement amount by the X direction scanning electromagnet 102 (total X direction movement amount of the beam center axis) is Y The amplitude is substantially equal to the amount of movement of the beam center axis by the direction scanning electromagnet 103 (the amount of movement of the beam center axis in the Y direction) and the phase is shifted by 90 °. As a result, the beam center axis is controlled to draw a circular locus on the irradiation surface of the irradiation target P.
[0050]
At this time, the two X-direction scanning electromagnets 101 and 102 are connected in series to the X-direction scanning power source 105 as described above, so that the beam center axis is moved by the downstream X-direction scanning electromagnet 102. The amplitude of the amount becomes slightly larger (for example, 1.2 times) than the amplitude of the beam center axis moving amount by the Y direction scanning electromagnet 103, and the amplitude of the beam center axis moving amount by the upstream X direction scanning electromagnet 101 is always above. The proportional relationship (for example, 0.2 times) is maintained in the opposite direction to the amplitude of the beam center axis movement amount of the X-direction scanning electromagnet 102. In this way, the above-described X-direction total movement amount of the beam center axis and the Y-direction movement amount of the beam center axis movement amount are substantially equal.
[0051]
FIG. 1 is an explanatory diagram showing the passing behavior of a charged particle beam realized by the excitation control as described above, and schematically shows the beam axis passing range and the beam passing range in the X-direction scanning plane of the beam. is there. In addition, only the area | region of the magnetic pole of each scanning electromagnet 101,102,103 is shown collectively. In the portion where the X-direction scanning electromagnet 101 is located, the vertical direction of the paper is the X direction, and the direction perpendicular to the paper is the Y direction. In the portion where the X-direction scanning electromagnet 102 and the Y-direction scanning electromagnet 103 are located, the left-right direction on the paper surface is the X direction, and the direction perpendicular to the paper surface is the Y direction. An alternate long and short dash line m is the center of the beam passage range, and when the deflection amount of all the scanning electromagnets is 0, the central axis of the beam coincides with the alternate long and short dash line m. A dotted line n indicates a passing range of the beam center axis in the X-direction scanning plane, and a solid line p indicates a beam passing range that is larger by the beam diameter around the beam center axis.
[0052]
In FIG. 1 and FIG. 2 described above, the beam is first deflected with a relatively small amplitude so as to be bent and shifted by the X-direction scanning electromagnet 101 on the most upstream side, and as a result, the scanning amplitude (in other words, in some time unit). If the beam axis passing range and the beam diameter are taken into account, the beam passing range (the same applies hereinafter) gradually increases toward the downstream. Thereafter, the X-direction scanning electromagnet 102 disposed on the downstream side deflects the beam with a relatively large amplitude so as to reduce the deviation of the beam position (in a direction in which the beam passage range decreases). As a result, the scanning amplitude decreases again downstream from the X-direction scanning electromagnet 102.
[0053]
At this time, as described above, the amount of deflection by the two X-direction scanning electromagnets 101 and 102 is maintained in a proportional relationship, so that the focal point where the amplitude of the beam center axis becomes 0 can be obtained. This is a scanning point in the X direction. The scanning amplitude decreases toward the focal position Q, becomes 0 at the focal position Q, and then increases again downstream thereof. As the ratio of the deflection amounts of the two X-direction scanning electromagnets 101 and 102 maintained in the proportional relationship as described above is decreased, the X-direction scanning point (focal position) Q moves further to the downstream side. In this example, the ratio of deflection amounts is adjusted by, for example, appropriately selecting the length of the magnetic pole in the beam traveling direction of the electromagnet and the number of turns of the coil, and the scanning point Q is approximately the horizontal direction of the Y-direction scanning electromagnet 103 as shown in FIG. It is set in advance so as to come to the center (or at least the vicinity thereof). The magnetic pole spacing of the Y-direction scanning electromagnet 103 is set to be as narrow as possible as long as it does not interfere with the beam passage range.
[0054]
The beams deflected by the scanning electromagnets 101, 102, and 103 and having the scanning amplitude gradually increased again from the scanning point Q in the Y-direction scanning electromagnet 103 as described above are further downstream of the Y-direction scanning electromagnet 103. The light enters the scatterer 104 and is scattered by the scatterer provided in the scatterer 104. As a result, the XY in-plane distribution of the particles constituting the beam spreads in a Gaussian distribution around the beam center axis, and the beam intensity distribution spreads as it goes downstream. That is, the beam passing range is further expanded (see FIG. 1). At this time, the beam intensity distribution at the irradiation surface position is a two-dimensional Gaussian distribution substantially in the XY direction, and its standard deviation is adjusted to about two-thirds of the radius of the circle drawn by the beam central axis, and the Gaussian distribution is circular. As a result of scanning, the average integrated beam intensity distribution over one round of beam scanning on the irradiation surface of the irradiation target P is made uniform within a circular region of about 70% of the scanning circle around the scanning center. .
[0055]
The beam emitted from the scatterer 104 is attenuated at a predetermined rate by passing through the ridge filter 5a, and a distribution according to the thickness of the affected part is given to the energy of the beam. Thereafter, the dose of the beam is measured by the dose monitor 5b (the accumulated passage amount and intensity distribution may be measured. The dose absorbed by the irradiation target P is controlled based on these values) and further input to the bolus 5c. Thus, the energy distribution according to the lower shape of the affected area is obtained (in other words, the dose distribution in the depth direction within the irradiation target P is adjusted). Then, after being shaped into a horizontal shape of the affected area by the collimator 5d (in other words, the lateral dose distribution in the irradiation target P is adjusted), the irradiation target (patient's affected area) P is irradiated.
[0056]
In the above description, the X-direction scanning electromagnet 101 constitutes the first variable deflection means for variably deflecting the amount of incident charged particle beam in the X-direction according to the claims, and the X-direction scanning electromagnet 102. Comprises a second variable deflection means provided downstream of the first variable deflection means and variably deflects the amount of deflection of the charged particle beam deflected by the first variable deflection means in the X direction, and is configured in the Y direction. The scanning electromagnet 103 is provided on the downstream side of the second variable deflection unit, and constitutes a third variable deflection unit that variably deflects the amount of deflection of the charged particle beam deflected by the second variable deflection unit in the Y direction. To do.
[0057]
Also, the X direction scanning power supply 10 5 Constitutes a single excitation power source common to the first scanning electromagnet and the second scanning electromagnet, and the deflection amount by the first scanning electromagnet and the deflection amount by the second scanning electromagnet The Proportional relationship In The first deflection control means for controlling the first and second scanning electromagnets is also configured to maintain, and further, the deflection amount by the first variable deflection means and the deflection amount by the second variable deflection means, The Proportional relationship In The first and second variable deflection means are maintained so that the scanning point of the charged particle beam after passing through the second variable deflection means is at least near the center of the third variable deflection means. The second deflection control means for controlling is also configured.
[0058]
Next, the effect of this embodiment is demonstrated.
[0059]
(1) Miniaturization of other beam deflection means (deflection electromagnet, quadrupole electromagnet)
As described above, in the charged particle irradiation apparatus 1 of the present embodiment, the beam is deflected so as to bend the beam in the X direction by the X-direction scanning electromagnet 101 on the most upstream side (so as to increase the beam passage range). After that, the downstream X-direction scanning electromagnet 102 deflects the beam in the X direction so as to reduce the deviation of the beam position (reduces the beam passage range), thereby further entering the downstream Y-direction scanning electromagnet 103. The beam scanning point Q is positioned. As a result, the X-direction beam passing range in the Y-direction scanning electromagnet 103 is reduced, and after that scanning point Q, the beam passing area passes through the Y-direction scanning electromagnet 103 and expands again in the X direction to a predetermined size. The particle beam is introduced into the collimator 5d.
[0060]
Thus, unlike the conventional structure (Japanese Patent Laid-Open No. 10-282300) that uses a deflection electromagnet or a quadrupole electromagnet that originally does not have a very large beam focusing function, the X-direction scanning electromagnet 102 having a high beam focusing function causes a beam passing range in the X direction. , The transport distance can be reduced while the beam position deviation is reduced after the beam is bent by the X-direction scanning electromagnet 101 and the position of the X-direction beam passage range at that time is reduced. The maximum value can be reduced. Thereby, compared with the said conventional structure, size reduction (reduction of the dimension in a X direction) of the deflection electromagnet 2C as another deflection | deviation means provided in a transport path | route can be achieved. As a result, the deflection of the support structure (rotary gantry 6 in this example) due to its own weight can be reduced, so that the beam irradiation accuracy due to the deflection can be prevented from being lowered.
[0061]
(2) Cost reduction
This effect will be described in detail below with reference to a comparative example.
[0062]
FIG. 5 shows an overall schematic structure of a charged particle irradiation apparatus according to a comparative example of this embodiment, which is substantially equivalent to the original charged particle irradiation apparatus provided with one X-direction scanning electromagnet and one Y-direction scanning electromagnet. FIG. 6 is a conceptual side view, and FIG. 6 schematically shows a beam axis passing range and a beam passing range in the X-direction scanning plane of the beam, respectively corresponding to FIGS. 2 and 1 described above. It is. 5 and 6, parts equivalent to those in the charged particle irradiation apparatus 1 according to the above-described embodiment are denoted by reference numerals added with “′” as a subscript, and description thereof will be omitted as appropriate.
[0063]
5 and 6, in the charged particle irradiation apparatus 1 ′ of this comparative example, only two of the X-direction scanning electromagnet 102 ′ and the Y-direction scanning electromagnet 103 ′ are arranged in the vertical direction in this order as scanning electromagnets. Further, a scatterer 104 ′ is disposed downstream of the Y-direction scanning electromagnet 103 ′.
[0064]
The beam is deflected by the X-direction scanning electromagnet 102 ′ and the Y-direction scanning electromagnet 103 ′ in the same manner as the irradiation method of the charged particle irradiation apparatus 1 of the above embodiment, and the beam center axis draws a circular locus on the irradiation surface. That is, there is a scanning point Q ′ in the X direction at the horizontal center (or at least in the vicinity thereof) of the upstream X direction scanning electromagnet 102 ′, and the scanning amplitude increases toward the downstream side from this scanning point Q ′. . As a result, the X-direction beam passing range at the position of the Y-direction scanning electromagnet 103 ′ located downstream of the X-direction scanning electromagnet 102 ′ must be relatively large, and the magnetic pole in the X direction of the Y-direction scanning electromagnet 103 ′ must be increased. The interval also increases.
[0065]
At this time, the power consumption of the scanning electromagnet is generally proportional to, for example, the square of the magnetic pole spacing in the magnetic field generation direction. Therefore, in this comparative example, the power consumption of the Y-direction scanning electromagnet 103 ′ is that of the X-direction scanning electromagnet 102 ′. For example, it reaches about 5 times. For this reason, the total power consumption of the two X-direction scanning electromagnets 102 ′ and Y-direction scanning electromagnets 103 ′ increases remarkably.
[0066]
Further, regarding the power supply capacity, generally, the power supply capacity of the scanning magnet is proportional to, for example, the magnetic pole spacing in the magnetic field generation direction. Therefore, the power supply capacity required for the Y-direction scanning electromagnet power supply 107 ′ for exciting the Y-direction scanning electromagnet 103 ′. Of the X-direction scanning electromagnet power source 105 'for exciting the X-direction scanning electromagnet 102' reaches, for example, several times (3 to 5 times). For this reason, a particularly large power supply is required for the Y-direction scanning electromagnet power supply 107 ′. In some cases, the Y-direction scanning electromagnet power supply 107 ′ cannot be obtained in a normal market and needs to be manufactured separately, resulting in an increase in equipment cost (initial cost).
[0067]
On the other hand, in the charged particle irradiation apparatus 1 of the present embodiment, the X-direction scanning electromagnet 101, the X-direction from the total two of the X-direction scanning electromagnet 102 ′ and the Y-direction scanning electromagnet 103 ′ of the comparative example. The total number of scanning electromagnets 102 and Y-direction scanning electromagnets 103 is increased by one. However, according to the study by the inventors of the present application, in the charged particle irradiation apparatus 1 of the present embodiment, the magnetic pole interval is set to the above by reducing the X-direction beam passage range in the Y-direction scanning electromagnet 103 on the most downstream side as described above. It was found that the Y-direction scanning electromagnet 103 ′ of the comparative example can be reduced to, for example, about ½. As a result, the power consumption of the Y-direction scanning electromagnet 103 can be reduced to about ３ of the Y-direction scanning electromagnet 103 ′ of the comparative example. On the other hand, since the X-direction scanning electromagnet 101, which is a new addition compared with the comparative example, has a small deflection amount and is extremely small as described above, the power consumption of the X-direction scanning electromagnets 101 and 102 is reduced. Even if it adds up, it does not reach twice the power consumption of the X direction scanning electromagnet 102 'of the comparative example. As a result, the total power consumption of the X-direction scanning electromagnet 101, the X-direction scanning electromagnet 102, and the Y-direction scanning electromagnet 103 is reduced to the two X-direction scanning electromagnets 102 'and Y-direction scanning electromagnet 103' in the comparative example. For example, the total power consumption can be reduced to about ½, and the operating cost (running cost) can be reduced.
[0068]
Further, regarding the power source capacity, according to the study by the inventors of the present application, in the charged particle irradiation apparatus 1 of the present embodiment, as described above, the X-direction beam passing range of the Y-direction scanning electromagnet 103 on the most downstream side is as described above. Since the magnetic pole spacing is reduced by the reduction, the power capacity of the Y-direction scanning power source 107 can be reduced to about 60% of the excitation power source 107 ′ of the Y-direction scanning electromagnet 103 ′ of the comparative example, and the cost can be reduced. It can be significantly reduced. On the other hand, since the X-direction scanning electromagnet 101, which is a new addition compared with the comparative example, has a small amount of deflection and needs only a very small size, the power capacity to be increased for the X-direction scanning electromagnet is the above comparison. Example X-directional scanning power supply 10 5 About 1/3 of the power supply capacity of ′ is sufficient. Regarding the power capacity used for the X-direction scanning electromagnet 102, the beam passing range at the position of the X-direction scanning electromagnet 102 is larger in the X direction than the X-direction scanning electromagnet 102 'of the comparative example. It is necessary to expand the effective magnetic field range of the scanning magnet magnetic field. However, in this case, since the expansion is in the direction parallel to the magnetic pole surface (X direction), the increase in the power supply capacity is not as great as when the magnetic pole spacing is increased, and the X-direction scanning power supply 10 of the above comparative example is not. 5 A thing that is not much different from ′ is enough. As a result, the three scanning electromagnets 101, 102, and 10 are comprehensively viewed. 3 The equipment cost (initial cost) required for the power supplies 105 and 107 used for excitation of the power supply 105 is the power supply 105 used for excitation of the two scanning electromagnets 102 'and 103' of the comparative example. ′ 107 ′ It has been found that it can be at least approximately equal to or smaller than the necessary equipment cost.
[0069]
As described above, in the charged particle irradiation apparatus 1 of the present embodiment, the operating cost (running cost) is reduced as compared with the comparative example provided with one X-direction scanning electromagnet and one Y-direction scanning electromagnet. And the equipment cost can be at least approximately equal or smaller. Therefore, when viewed in total, the cost can be reduced more reliably than the comparative example.
[0070]
(3) Other
1. The effect of common X-direction scanning power supply
As described above, in the present invention, the deflection amount by the X-direction scanning electromagnet 101 and the deflection amount by the X-direction scanning electromagnet 102 are The Proportional relationship In Need to be maintained. In this embodiment, two X-direction scanning electromagnets 101 and 102 are connected in series to a common X-direction scanning power source 105, so that the amount of beam deflection by the respective scanning electromagnets 101 and 102 is particularly adjusted. Even if it is not performed, the proportional relationship can be easily achieved. Therefore, the operation is simplified and the possibility of erroneous irradiation due to deviation can be reduced.
[0071]
2. Effect of scatterer position
In general, in the lateral beam expansion method combining beam scanning and beam diameter expansion, the quality of the irradiation beam that reaches the irradiation target is deteriorated as the scatterer and the beam scanning position are separated from each other. For example, when two scanning electromagnets are used, if a scatterer is arranged upstream or downstream of the scanning electromagnets, one of the scanning electromagnets will be far from the scatterer, and the angular distribution of the irradiation beam will be widened. When the beam is cut out with this collimator, the cut (penumbra) becomes large, and the irradiation performance deteriorates. In the present embodiment, as shown in FIG. 1, the distance between the X-direction scanning point Q and the scatterer 104 can be made smaller than in the comparative example of FIG. Can be reduced. As a result, the spread of the beam angle distribution at the irradiation surface position of the irradiation target P can be reduced. Therefore, when the beam is cut out in the horizontal direction by the collimator 5d, the cut in the horizontal beam intensity distribution (= half of the dose distribution in the irradiation target). (Shadow) can be reduced, and the irradiation accuracy can be improved. In addition, an irradiation apparatus that scans a large area and irradiates a wide area can be realized.
[0072]
At this time, in this embodiment, the ratio of the deflection amounts of the X-direction scanning electromagnets 101 and 102 is set so that the X-direction scanning point Q is not the center of the Y-direction scanning magnet 103 but the center of the scatterer 104 or its vicinity. Can also be adjusted. In this case, although the magnetic pole interval of the Y-direction scanning electromagnet 103 is slightly increased, there is an effect that the penumbra of the dose distribution in the irradiation target P can be further reduced.
[0073]
In the above-described embodiment, the scatterer 104 is disposed on the downstream side of the Y-direction scanning electromagnet 103 which is the most downstream side. However, the present invention is not limited to this, and the X-direction scanning electromagnet 102 and the Y-direction scanning electromagnet 103 are not limited thereto. It may be provided between them. Hereinafter, this modification will be described with reference to FIGS.
[0074]
FIG. 7 is a diagram schematically showing a beam axis passing range and a beam passing range in the X-direction scanning plane of the charged particle irradiation apparatus according to this modification, and corresponds to FIG. 1 of the above embodiment. In FIG. 7, parts that are the same as those in the charged particle irradiation apparatus 1 according to the above embodiment are given the same reference numerals, and descriptions thereof are omitted as appropriate.
[0075]
In FIG. 7, in the charged particle device of this modification, the scatterer 104 is located downstream of the X direction scanning electromagnet 102 and upstream of the Y direction scanning electromagnet 103 (in other words, the X direction scanning electromagnet 102 and the Y direction scanning electromagnet 103. Between). Other points are substantially the same as those of the charged particle device 1 of the above embodiment.
[0076]
The beam is deflected by the X direction scanning electromagnets 101 and 102 and the Y direction scanning electromagnet 103 in the same manner as the irradiation method of the charged particle irradiation apparatus 1 of the above embodiment. At this time, the XY in-plane scanning magnet 102 and the Y-direction scanning electromagnet 103 are scattered by the scatterer 104, and the XY in-plane distribution of the particles constituting the beam spreads around the beam central axis in a Gaussian distribution and downstream. The beam intensity distribution spreads as it progresses. Finally, the beam center axis draws a circular locus on the irradiation surface of the irradiation target P.
[0077]
Also in the present modification, as in the above-described embodiment, the basic effects of the present invention (1) the effect of reducing the size of other beam deflecting means and (2) reducing the cost can be obtained.
[0078]
In other words, after the beam is bent in the X direction by the X-direction scanning electromagnet 101 on the most upstream side and deflected so as to shift the position, the displacement of the beam position in the X direction is reduced by the downstream X-direction scanning magnet 102. The beam scanning point Q is positioned inside the Y-direction scanning electromagnet 103 on the downstream side via the scatterer 4 to reduce the X-direction beam passing range in the Y-direction scanning electromagnet 103. This makes it possible to reduce the size of the deflection electromagnet 2C as compared with the conventional structure using a deflection electromagnet or a quadrupole electromagnet that originally does not have a large beam focusing function. In addition, this can reduce the operating cost compared to the original structure including one X-direction scanning magnet and one Y-direction scanning magnet, and can at least substantially equal or reduce the equipment cost, Cost reduction can be achieved in total.
[0079]
In addition, since the scatterer unit is upstream of the Y-direction scanning electromagnet 3, the beam passage range when passing through the Y-direction scanning electromagnet 3 is slightly larger than that in the above embodiment, but overall, It is possible to obtain substantially the same effect as the above embodiment. In particular, for example, when compared with a conventional charged particle beam irradiation apparatus (for example, Japanese Patent Laid-Open No. 10-211292) on the assumption that the scatterer is between the X-direction scanning electromagnet and the Y-direction scanning electromagnet, The effect of is remarkable.
[0080]
FIG. 8 shows a charged particle irradiation apparatus according to a comparative example of the present embodiment, which is substantially equivalent to the charged particle irradiation apparatus according to the above-mentioned Japanese Patent Application Laid-Open No. 10-211292, provided with one X-direction scanning electromagnet and one Y-direction scanning electromagnet. 3 schematically shows a beam axis passing range and a beam passing range in the X-direction scanning plane of the beam. In FIG. 8, parts equivalent to those in the charged particle irradiation apparatus 1 according to the above-described embodiment are denoted by reference numerals added with “″” as a subscript, and description thereof will be omitted as appropriate.
[0081]
In FIG. 8, in the charged particle irradiation apparatus of this comparative example, only two X-direction scanning electromagnets 102 ″ and Y-direction scanning electromagnets 103 ″ are arranged close to each other in this order in the vertical direction as scanning electromagnets. The scatterer 104 "is disposed between the 102" and the electromagnet 103 ". In this case, as in the comparative example described above with reference to FIG. Although the scanning point Q ″ is present and the scanning amplitude increases toward the downstream side, the scanning amplitude is further expanded by the scatterer 104 ″ before entering the Y-direction scanning electromagnet 103 ″. The X-direction beam passing range at the position of the electromagnet 103 ″ is considerably increased, and the magnetic pole spacing in the X direction of the Y-direction scanning electromagnet 103 ″ is also considerably increased.
[0082]
On the other hand, in the charged particle irradiation apparatus of this modification shown in FIG. 7, as can be seen from the comparison with FIG. 8, the magnetic pole is reduced by reducing the X-direction beam passing range in the Y-direction scanning electromagnet 103 on the most downstream side. The interval can be greatly reduced as compared with the Y-direction scanning electromagnet 103 ″ of the comparative example. Therefore, it can be seen that the effects described in the above (1) and (2) can be obtained. That is, the scatterer 104 is scanned in the X-direction. Even when it is assumed to be disposed between the electromagnet 102 and the Y-direction scanning electromagnet 103, the magnetic pole interval of the Y-direction scanning electromagnet 103 can be reduced, and the effects of cost reduction and downsizing of other deflection means can be achieved. Can be planned.
[0083]
In addition to the above, this modification also has the following effects.
[0084]
That is, as can be seen by comparing FIG. 7 and FIG. 1, in this modification, the distance between the scatterer 104 and the irradiation surface is larger than that of the embodiment shown in FIG. As a result, the amount of scattering required to form the same beam intensity distribution on the irradiation surface is reduced, and the scatterer 104 can be made thinner than in the above embodiment. As a result, the energy loss of the beam in the scatterer 104 is reduced, and the energy of the beam reaching the irradiation surface is increased. Therefore, the reaching depth of the beam in the irradiation target P becomes deep, and irradiation can be performed on a target deeper than the above embodiment.
[0085]
In the above, the irradiation method using the configuration including the three scanning electromagnets 101, 102, 103 and the scatterer 104 has been described as an example. However, the presence or absence of the scatterer is not essential to the present invention, and the scattering It goes without saying that the effects (1) and (2) inherent in the above-described invention can be obtained regardless of the presence or absence of the body 104.
[0086]
In the above, the case where the two X-direction scanning electromagnets 101 and 102 are excited by the single X-direction scanning power source 105 has been described as an example. However, the present invention is not limited to this. , 102 may be separated (a first excitation power source for exciting the X-direction scanning electromagnet 101 as the first operation electromagnet and a second excitation power source for exciting the X-direction scanning electromagnet 102 as the second operation electromagnet). . In this case, each excitation current is adjusted by changing the amplification factor, and thereby the scanning point position can be adjusted as desired. Therefore, even when there is a change in the equipment conditions between the X-direction scanning electromagnet 101 and the X-direction scanning electromagnet 102 or there is a magnet design error, the scanning point can be adjusted so as not to shift, and the beam Y-direction can be adjusted. It is possible to avoid collision with the magnetic poles of the scanning electromagnet 103 and maintain irradiation accuracy. At this time, if each power source is controlled by a common power source control means (single signal source), it is not necessary to adjust the phase of the two X-direction scanning electromagnets 101 and 102, and the operation is simple. In addition, the possibility of erroneous irradiation due to phase shift can be reduced.
[0087]
Further, the case where scanning is performed so that the beam center trajectory is circular on the irradiation surface has been described as an example. However, the present invention is not limited to this, and an arbitrary trajectory may be drawn such as scanning in the same manner as a television. Even in this case, by making the beam deflection amounts by the two X-direction scanning electromagnets 101 and 102 proportional, the X-direction scanning point position Q does not change, and the same effect as in the present embodiment can be obtained.
[0088]
Further, the above description has been given by taking as an example the case where the present invention is applied to a rotating gantry that rotates the irradiation device to change the irradiation direction. However, the present invention is not limited to this, and the irradiation direction is fixed to the irradiation device. Even applicable. In this case, generally, an apparatus for deflecting the beam is not provided between the X-direction scanning electromagnets 101 and 102, but the same effect as the present embodiment can be obtained.
[0089]
【The invention's effect】
According to the present invention, since the second scanning electromagnet having a high beam focusing function is used to rapidly deflect the beam in the X direction so as to reduce the positional deviation of the beam, the beam is once bent and displaced by the first scanning electromagnet. Thus, the maximum value of the beam passing range when the beam is deflected so as to reduce the deviation of the beam position after being deflected can be reduced. Therefore, it is possible to reduce the size of other beam deflecting means such as a deflection electromagnet or a quadrupole electromagnet normally provided between them. In addition, the total power consumption of the first to third scanning electromagnets is reduced to, for example, about ½ the total power consumption of the original two X-direction and Y-direction scanning electromagnets (running cost). ) And the equipment cost (initial cost) required for the excitation power supply for the three first to third scanning magnets is reduced to the equipment required for the original excitation power supply for the two X and Y direction scanning magnets. Since it can be at least substantially equal to or smaller than the cost, the cost can be reduced.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a passing behavior of a charged particle beam realized by excitation control of a charged particle irradiation apparatus according to an embodiment of the present invention.
FIG. 2 is a conceptual side view showing an overall schematic structure of a charged particle irradiation apparatus according to an embodiment of the present invention.
FIG. 3 is a diagram illustrating an example of a temporal change in excitation current supplied to an X-direction scanning magnet and a Y-direction scanning magnet by an X-direction scanning electromagnet power source and a Y-direction scanning electromagnet power source.
FIG. 4 is a diagram illustrating an example of a temporal change in the amount of movement of the beam center axis on the irradiation surface caused by beam deflection by three scanning electromagnets.
FIG. 5 shows an overall schematic structure of a charged particle irradiation apparatus according to a comparative example of the present embodiment, which is substantially equivalent to an original charged particle irradiation apparatus provided with one X-direction scanning electromagnet and one Y-direction scanning electromagnet. It is a conceptual side view.
FIG. 6 schematically shows a beam axis passing range and a beam passing range in the X-direction scanning plane of a beam.
FIG. 7 schematically shows a beam axis passing range and a beam passing range in an X direction scanning plane of a charged particle irradiation apparatus according to a modification in which a scatterer is provided between an X direction scanning electromagnet and a Y direction scanning electromagnet. FIG.
FIG. 8 schematically shows a beam axis passing range and a beam passing range of an X direction scanning plane beam of a charged particle irradiation apparatus according to a comparative example including one X direction scanning magnet and one Y direction scanning magnet. It is a thing.
[Explanation of symbols]
101 X-direction scanning electromagnet (first scanning electromagnet, first variable deflection means)
102 X-direction scanning electromagnet (second scanning electromagnet, second variable deflection means)
103 Y-direction scanning electromagnet (third scanning electromagnet, third variable deflection means)
104 Scatterer
10 5 X direction scanning power supply (single excitation power supply, first deflection control means, second deflection control means)
P Irradiation target (affected area)

Claims (6)

In a medical charged particle irradiation apparatus that irradiates an affected area of a patient with charged particles,
A first scanning electromagnet that deflects an incident charged particle beam so as to shift the position by bending the beam in one direction in a plane perpendicular to the beam traveling direction;
The charged particle beam provided at the downstream side of the first scanning electromagnet and deflected by the first scanning electromagnet is reduced in the downstream side by reducing the deviation of the beam position, contrary to the deflection by the first scanning electromagnet. A second scanning electromagnet that deflects in the one direction to form a focus ;
A charged particle beam which is provided downstream from the second scanning electromagnet and is deflected in the one direction by the second scanning electromagnet and whose passing range in the one direction is reduced is a plane perpendicular to the beam traveling direction. A charged particle irradiation apparatus for medical use, comprising: a third scanning electromagnet that deflects in another direction orthogonal to the one direction. In a medical charged particle irradiation apparatus that irradiates an affected area of a patient with charged particles,
A first scanning electromagnet that deflects an incident charged particle beam so as to shift the position by bending the beam in one direction in a plane perpendicular to the beam traveling direction;
The charged particle beam provided at the downstream side of the first scanning electromagnet and deflected by the first scanning electromagnet is reduced in the downstream side by reducing the deviation of the beam position, contrary to the deflection by the first scanning electromagnet. A second scanning electromagnet that deflects in the one direction to form a focus ;
A charged particle beam which is provided downstream from the second scanning electromagnet and is deflected in the one direction by the second scanning electromagnet and whose passing range in the one direction is reduced is a plane perpendicular to the beam traveling direction. A third scanning electromagnet that deflects in another direction orthogonal to the one direction in
To maintain the deflection amount by the second scanning magnets and the deflection amount by the first scanning magnet proportional, and characterized by having a first deflecting control means for controlling these first and second scanning magnets Medical charged particle irradiation device.   3. The medical charged particle irradiation apparatus according to claim 1, wherein a scatterer that scatters a charged particle beam is provided downstream from the third scanning electromagnet. 4.   3. The medical charged particle irradiation apparatus according to claim 1, wherein a scatterer that scatters a charged particle beam is provided downstream of the second scanning electromagnet and upstream of the third scanning electromagnet. Medical charged particle irradiation device.   3. The medical charged particle irradiation apparatus according to claim 2, wherein the first deflection control unit includes a single excitation power source common to the first scanning electromagnet and the second scanning electromagnet, and the first scanning electromagnet and the second scanning electromagnet. The scanning electromagnet is a medical charged particle irradiation apparatus, wherein each excitation coil is connected in series to the single excitation power source.   3. The medical charged particle irradiation apparatus according to claim 2, wherein the first deflection control means includes a first excitation power source and a second excitation power source that supply power to the first scanning electromagnet and the second scanning electromagnet, respectively. A charged particle irradiation apparatus for medical use, comprising a power supply control means common to the first and second excitation power supplies.

Images