JP2004121654A - Apparatus for irradiating electric charged particle for medical use - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a cost without enlarging other beam deflection means. <P>SOLUTION: An electric charged particle irradiation apparatus for medical use for irradiating the irradiation object P of a patient with electric charged particles includes: an X-direction scanning electromagnet 101 for deflecting an incident electric charged particle beam to transfer a position by bending the beam in an X-direction; an X-direction scanning electromagnet 102 which is arranged on the downstream side of the X-direction scanning electromagnet 101, and deflects in an X-direction the electric charged particle beam deflected by the electromagnet 101, so as to reduce the positional deviation of the beam; and a Y-direction scanning electromagnet 103 which is arranged on the downstream side of the X-direction scanning electromagnet 102, and deflects to the Y-direction the electric charged particle beam deflected by the electromagnet 102. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD 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, to 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 and tumors by irradiating the affected part of a patient with charged particle beam beams such as protons and carbon ions.The charged particles generated by an ion source and accelerated by an accelerator such as a synchrotron After the irradiation range 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 forms the irradiation field of the charged particle beam in accordance with the three-dimensional shape of the irradiation target (affected part) and adjusts the dose distribution. , A Z-axis), a horizontal beam forming unit for shaping an irradiation range in a plane (XY plane having an X-axis and a Y-axis), and an irradiation range in a traveling direction (Z-axis) of a charged particle beam. And a range adjuster that forms
[0004]
The range adjuster adjusts the energy of the charged particle beam corresponding to the depth of the irradiation target, and adjusts the charged particle beam according to the shape of the irradiation target in the traveling direction (depth direction) of the charged particle beam. It is to shape.
[0005]
The horizontal beam forming unit expands the charged particle beam in a plane (XY plane) perpendicular to the traveling direction of the charged particle beam, and then cuts out the expanded charged particle beam with a collimator. 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, and a method of combining them.
[0006]
In the method of scanning a beam, generally, two beam deflecting means are often arranged so that their respective deflecting surfaces are perpendicular to each other. In particular, when irradiating a high energy beam such as a proton or a heavy particle, the beam is deflected. An electromagnet (scanning electromagnet) is often used as the deflecting means. For example, an X-direction scanning electromagnet having a magnetic pole surface perpendicular to the Y direction and generating a magnetic field in the Y direction and deflecting the beam in the X direction is arranged 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 position of the beam in the X direction 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. The scanning point of the beam in the Y direction is substantially near the center of the downstream Y-direction scanning electromagnet.
[0007]
In such a configuration, the beam scanning range of the downstream Y-direction scanning electromagnet is larger than that of the upstream side by the beam scanning by the upstream X-direction scanning electromagnet. Must be increased. Here, in the scanning electromagnet, since the magnetic resistance generally increases as the magnetic pole interval in the magnetic field generation direction increases, the power consumption increases in proportion to the power (for example, square) of the magnetic pole interval. For this reason, the power consumption in the Y-direction scanning electromagnet significantly increases due to the increase in the magnetic pole interval in the X direction as described above, and the operating cost (running cost) increases. In addition, as for the power supply for exciting the scanning electromagnet, the power supply capacity represented by the product of the maximum voltage and the maximum current is generally increased in proportion to the magnetic pole interval in the direction in which the magnetic field is generated. In the above-described configuration, it is necessary to prepare a power source having an extremely large power supply capacity as an exciting power source for the Y-direction scanning electromagnet, which increases the equipment cost (initial cost).
[0008]
To cope with this, conventionally, the X-direction scanning electromagnet and the Y-direction scanning electromagnet are arranged at a large distance, and the beam in the X-direction of the deflection electromagnet and the quadrupole electromagnet provided between these two scanning electromagnets. Japanese Patent Application Laid-Open No. H11-163,087 proposes a technique that utilizes a convergence function to reduce the beam passage range in the X direction near the downstream Y-direction scanning electromagnet.
[0009]
In this conventional technique, a beam is bent in the X direction by an X-direction scanning electromagnet and deflected so as to shift the position, and then the beam is converged in the X direction while passing through them by utilizing the beam convergence function of a bending electromagnet or a quadrupole electromagnet. It is gradually deflected so as to reduce the positional deviation, and focuses once near the downstream Y-direction scanning electromagnet. As a result, 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 of the downstream Y-direction scanning electromagnet is reduced. Then, after the focal point, the particle beam that has passed through the Y-direction scanning electromagnet and has a larger beam passing range in the X direction again 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]
JP-A-10-282300 (paragraph number
[0011]
And FIG. 7)
[Problems to be solved by the invention]
In the above prior art, the X-direction beam convergence function of the deflection electromagnet and the quadrupole electromagnet provided between the X-direction scanning electromagnet and the Y-direction scanning electromagnet is used to focus once in the vicinity of the downstream Y-direction scanning electromagnet. The beam passage range in the directional scanning electromagnet is reduced. As a result, it is possible to prevent an increase in power consumption and an increase in the excitation power supply capacity due to an increase in the magnetic pole interval in the X direction in the Y-direction scanning electromagnet, thereby achieving cost reduction.
[0013]
However, since the beam convergence function of the above-mentioned bending magnets and quadrupole magnets is not so large in nature, the beam position of the charged particle beam once deflected so as to shift the position by bending the beam with the X-direction scanning electromagnet is reversed. While deflecting to be smaller, 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 bending or quadrupole electromagnets becomes larger. Become. That is, although the size of the scanning electromagnet can be reduced, the size of other beam deflecting means (in this example, a quadrupole electromagnet or a deflection electromagnet having a large structure) increases in the X direction. For this reason, the deflection of the support structure increases due to the increase in their own weight (particularly in a rotating gantry as in this known example), and as a result, it becomes difficult to improve the beam irradiation accuracy.
[0014]
SUMMARY OF THE INVENTION An object of the present invention is to provide a medical charged particle irradiation apparatus capable of reducing costs 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 medical charged particle irradiation apparatus for irradiating an affected part of a patient with charged particles, wherein the charged particle beam is incident on a plane perpendicular to the beam traveling direction. A first scanning electromagnet that bends the beam in one direction to deflect the beam so as to shift the position, and a charged particle beam provided downstream of the first scanning electromagnet and deflected by the first scanning electromagnet. A second scanning electromagnet that deflects to reduce the deviation of the beam position in the direction of, and a charged particle beam that is provided downstream of the second scanning electromagnet and is deflected by the second scanning electromagnet, A third scanning electromagnet that deflects in another direction orthogonal to the one direction in a plane perpendicular to the beam traveling direction.
[0016]
In the present invention, the beam is deflected by, for example, bending in the X direction by the first scanning electromagnet to shift the position, and then deflected by the second scanning electromagnet on the downstream side so as to reduce the deviation of the beam position in the X direction. This makes it possible to focus once, for example, near the Y-direction third 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 of the downstream third scanning electromagnet is reduced, and after the focal point, the third scanning electromagnet is moved. , 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 sharply 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 originally has a beam focusing function not so large as in the conventional structure. Therefore, it is possible to reduce the transport distance while reducing the displacement of the beam after the beam is once displaced by bending the beam by the first scanning electromagnet, and to reduce the maximum value of the beam passage range at that time. Can be. Therefore, it is possible to reduce the size of other beam deflecting means such as a deflection electromagnet or a quadrupole electromagnet usually 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 Since the number of the scanning electromagnets (Y direction) is increased by one, the power consumption and the power supply capacity are separately added.
[0019]
However, in terms of 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 in the downstream Y-direction scanning electromagnet. The magnetic pole interval in the X direction, which is the direction in which the magnetic field is generated, 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 electromagnet reaches, for example, about five times that of the X-direction scanning electromagnet. Therefore, the total power consumption of the two X-direction scanning electromagnets and two Y-direction scanning electromagnets is significantly increased.
[0020]
In the present invention, as described above, the distance between the magnetic poles can be reduced to, for example, about 元 of the original structure by reducing the X-direction beam passage range of the third scanning electromagnet on the most downstream side. The power consumption of the third scanning electromagnet can be reduced to about 1/3 of the electromagnet. On the other hand, the first additional scanning electromagnet, which has a small amount of deflection and needs only an extremely small size, is sufficient even if the power consumption of the first and second scanning electromagnets is summed up. It does not reach twice the power consumption of the electromagnet. As a result, the total power consumption of the first to third scanning electromagnets can be reduced to, for example, about １ ／ of the total power consumption of the original two X-direction and Y-direction scanning electromagnets. Cost) can be reduced.
[0021]
Regarding the power supply capacity, in the above-described original structure in which one X-direction scanning electromagnet and one Y-direction scanning electromagnet are arranged, as described above, the power supply capacity is, for example, proportional to the magnetic pole interval in the magnetic field generation direction. Therefore, the power supply capacity required for the excitation power supply of the Y-direction scanning electromagnet reaches, for example, about several times (3 to 5 times) the excitation power supply of the X-direction scanning electromagnet. For this reason, the Y-direction scanning electromagnet requires a particularly large power supply, and in some cases, it is not available in a normal market and needs to be separately manufactured, which increases the equipment cost (initial cost).
[0022]
In the present invention, since the gap between the magnetic poles is reduced by reducing the X-direction beam passage range of the third scanning electromagnet on the most downstream side as described above, the third scanning electromagnet is reduced to about 60% of the original Y-direction scanning electromagnet. The power capacity of the excitation power source for the scanning electromagnet can be reduced, and the cost can be significantly reduced. On the other hand, the first scanning electromagnet, which is a newly added component, has a small deflection amount and requires only an extremely small one, so the power supply capacity used for the first scanning electromagnet is the same as the power supply of the original X-direction scanning electromagnet. A capacity of about 1/3 of the capacity is sufficient, and a power supply capacity used for the second scanning electromagnet is not much different from the original X-direction scanning electromagnet. As a result, when viewed comprehensively, the equipment cost (initial cost) required for the excitation power supply of the first to third scanning electromagnets is reduced to the original excitation power supply of the two X- and Y-direction scanning electromagnets. It can be at least approximately equal to or less than the required equipment costs.
[0023]
As described above, in the present invention, the cost can be reduced without increasing the size of other beam deflecting means.
[0024]
(2) In order to achieve the above object, the present invention provides a medical charged particle irradiation apparatus for irradiating an affected part of a patient with charged particles, wherein the incident charged particle beam is focused on a plane perpendicular to the beam traveling direction. A first scanning electromagnet which bends the beam in one direction to deflect so as to shift the position, and a charged particle beam beam provided downstream of the first scanning electromagnet and deflected by the first scanning electromagnet, A second scanning electromagnet that deflects to reduce the deviation of the beam position in one direction, and a charged particle beam that is provided downstream of the second scanning electromagnet and deflected by the second scanning electromagnet, A third scanning electromagnet that deflects 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 a deflection amount by the second scanning electromagnet; So as to maintain a predetermined proportional relationship, and a first deflecting control means for controlling these first and second scanning magnets.
[0025]
By maintaining the proportional relationship between the amount of deflection by the first scanning electromagnet and the amount of deflection by the second scanning electromagnet, the beam is bent to increase the positional deviation → reduced positional deviation → the focus of the particle beam beam 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 for scattering a charged particle beam is provided downstream of the third scanning electromagnet.
[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 be incident on the scatterer from a wider range in more directions, and after the light is emitted from the scatterer. As a result of the beam outline becoming ambiguous, the angular distribution spread of the irradiation beam becomes large, and the dose distribution in the irradiation target after cutting out the beam by the collimator (the penumbra) becomes large, making it difficult to improve the irradiation accuracy.
[0028]
In the present invention, since the beam scanning point is substantially moved to the vicinity of the third scanning electromagnet, which is the focal position, as described in the above (1), by providing a scatterer downstream of the third scanning electromagnet, The distance between the scanning point and the scatterer can be reduced. Thereby, the penumbra of the dose distribution in the irradiation target can be reduced and the irradiation accuracy can be improved. In addition, an irradiation device that scans a large area and irradiates a wide area can be realized. In particular, when the beam scanning point is set in the vicinity of the scatterer, the penumbra of the dose distribution in the irradiation target can be made smaller, and the irradiation accuracy can be further improved.
[0029]
(4) In the above (1) or (2), and preferably, a scatterer for scattering a charged particle beam is provided downstream of the second scanning electromagnet and upstream of the third scanning electromagnet.
[0030]
By disposing the scatterer on the upstream side 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 required to form the same beam intensity distribution on the irradiation surface is reduced. be able to. Thereby, the thickness of the scatterer can be reduced, and the energy loss of the beam in the scatterer can be reduced. As a result, the energy of the beam reaching the irradiation surface increases, so that the beam reaches a deeper position within the irradiation target, so that a deeper target can be irradiated.
[0031]
(5) In (2) above, preferably, the first deflection control means includes a single excitation power supply common to the first scanning electromagnet and the second scanning electromagnet, and the first scanning electromagnet and the second scanning electromagnet include In the scanning electromagnet, each excitation coil is connected in series to the single excitation power supply.
[0032]
Thus, the beam deflection amounts of the first scanning electromagnet and the second scanning electromagnet can be easily made to have a proportional relationship without any particular adjustment. Therefore, the operation can be simplified, and the possibility of erroneous irradiation due to the deviation can be reduced.
[0033]
(6) In (2) above, preferably, the first deflection control means includes a first excitation power supply and a second excitation power supply for supplying power to the first scanning electromagnet and the second scanning electromagnet, respectively. Power supply control means common to the first and second excitation power supplies is provided.
[0034]
In the present invention, the excitation power supply for the first scanning electromagnet and the excitation power supply for 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 if the condition of the device between the first scanning electromagnet and the second scanning electromagnet is changed, or if there is a design error in the magnet, the scanning point can be adjusted so as not to shift, and the third scanning electromagnet of the beam can be adjusted. It is possible to avoid collision with the magnetic pole and maintain irradiation accuracy. At this time, since the first and second excitation power supplies are controlled by a single signal source called the second power supply control means, it is not necessary to adjust the phases of the first and second scanning electromagnets, and the operation is not performed. In addition to the simplification, the possibility of erroneous irradiation due to a phase shift can be reduced.
[0035]
(7) In order to achieve the above object, the present invention provides a medical charged particle irradiation apparatus for irradiating an affected part of a patient with charged particles, wherein the charged particle beam is incident on a plane perpendicular to the beam traveling direction. A first scanning electromagnet deflecting in one direction, and a second scanning electromagnet provided downstream of the first scanning electromagnet and deflecting the charged particle beam deflected by the first scanning electromagnet in the one direction And a charged particle beam provided downstream of the second scanning electromagnet and deflected by the second scanning electromagnet in a direction perpendicular to the one direction in a plane perpendicular to the beam traveling direction. A third scanning electromagnet for deflection.
[0036]
(8) In order to achieve the above object, the present invention provides a medical charged particle irradiation apparatus for irradiating an affected part of a patient with charged particles by deflecting an incident charged particle beam in an X direction variably. A first variable deflecting device, and a second variable deflecting device provided downstream of the first variable deflecting device for deflecting the amount of deflection of the charged particle beam deflected by the first variable deflecting device in the X direction. Means, and third variable deflecting means provided downstream of the second variable deflecting means and variably deflecting the amount of deflection of the charged particle beam deflected by the second variable deflecting means in the Y direction. Scanning of the charged particle beam so as to maintain a predetermined proportional relationship between the amount of deflection by the first variable deflection unit and the amount of deflection by the second variable deflection unit, and after passing through the second variable deflection unit Point ahead As the center or or at least near the third variable deflection means, and a second deflecting control means for controlling said first and second variable deflection means.
[0037]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0038]
The medical charged particle irradiation apparatus according to the present embodiment is applied to a known radiotherapy apparatus such as a proton beam therapy apparatus. Although not shown in detail, in this proton beam therapy system, a charged particle (eg, proton) beam generated by an injector is transported by a low energy beam, as described in, for example, JP-A-2001-353228. After passing through the apparatus, it is incident on the synchrotron, which is the main accelerator, and accelerated by the synchrotron to the energy required for treatment (typically 100 to 200 MeV). The charged particle beam emitted from the synchrotron is incident on the charged particle irradiation device (rotary irradiation device) of the present embodiment.
[0039]
FIG. 2 is a conceptual side view illustrating the overall schematic structure of the charged particle irradiation device 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 (the Z direction), and one direction in a plane perpendicular thereto is the X direction (the left-right direction in the plane of the paper of FIG. 2). A direction orthogonal to the X direction in the plane is defined as a Y direction (a direction perpendicular to the plane of FIG. 2).
[0040]
In FIG. 2, the charged particle irradiation apparatus 1 of this embodiment includes a deflection electromagnet 2A, 2B, 2C for beam transport, quadrupole electromagnets 3A, 3B, 3C for beam convergence, a vacuum particle chamber 4, an emission 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 around the rotation axis k, the irradiation direction can be changed.
[0041]
The emission nozzle 5 is provided with an X-direction scanning electromagnet (second scanning electromagnet) 102, a Y-direction scanning electromagnet (third scanning electromagnet) 103 disposed downstream thereof, and further disposed downstream thereof for beam expansion. A scatterer unit (scatterer) 104 that can change the thickness of the scatterer according to conditions is provided.
[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 (with the amount of deflection in the same plane as the deflection electromagnets 2A, 2B, and 2C). (Variable) deflection. At this time, the X-direction scanning electromagnet 101 deflects so as to shift the position by bending the beam, and the X-direction scanning electromagnet 102 deflects so as to reduce the above-described displacement of the beam position caused by the X-direction scanning electromagnet 101. The excitation coils (not shown) of these X-direction scanning electromagnets 102 and 103 are connected in series to a common X-direction scanning electromagnet power supply 105 via power lines 106a and 106b. Excited by electric power.
[0043]
The Y-direction scanning electromagnet 103 generates a magnetic field in the X direction, and deflects the beam in the Y direction (variably deflects the beam). An excitation coil (not shown) of the Y-direction scanning electromagnet 103 is connected to a Y-direction scanning electromagnet power supply 107 via a power supply line 108, and is excited by power from the Y-direction scanning electromagnet power supply 107.
[0044]
Next, the operation of the charged particle irradiation apparatus 1 of the present embodiment having the above configuration will be described.
[0045]
The beam input to the charged particle irradiation device 1 is transported downstream with its trajectory bent by the bending electromagnets 2A to 2C and adjusted in betatron oscillation by the quadrupole electromagnets 3A to 3C, and upstream of the X-direction scanning electromagnet 102. After exiting through the vacuum window from the vacuum chamber 4 into the air and passing through the air while being molded by various devices in the emission nozzle 5, the irradiation target P is irradiated.
[0046]
In such a beam transport process, the beam is deflected in the X direction in the same plane as the deflection electromagnet 7 by passing between the magnetic poles of the X-direction scanning electromagnets 101 and 102, and further, between the magnetic poles of the Y-direction scanning electromagnet 104. Is deflected in the Y direction.
[0047]
FIG. 3 is a diagram illustrating an example of a temporal change of an exciting current supplied to the X-direction scanning electromagnets 101 and 102 and the Y-direction scanning electromagnet 103 by the above-described X-direction scanning electromagnet power supply 105 and Y-direction scanning electromagnet power supply 107. FIG. 4 is a diagram showing an example of a temporal change in the movement amount of the beam center axis on the irradiation surface due to beam deflection by the three scanning electromagnets 101, 102, and 103.
[0048]
In FIG. 3, in this example, the X-direction scanning electromagnet power supply 105 and the Y-direction scanning electromagnet power supply 107 supply exciting currents whose time changes become sinusoidal, respectively, to the X-direction scanning electromagnets 101 and 102 and the Y-direction scanning electromagnet 103. And the phases of the X-direction exciting current and the Y-direction exciting current are shifted from each other by 90 °.
[0049]
The central axis of the beam on the irradiation surface moves in the X direction by an amount proportional to the amount of deflection of the X-direction scanning electromagnets 101 and 102, and moves in the Y direction by an amount proportional to the amount of deflection by the Y-direction scanning electromagnet 103. Thereby, as shown in FIG. 4, the sum of the movement amount of the beam center axis by the X-direction scanning electromagnet 101 and the movement amount of the beam center axis by the X-direction scanning electromagnet 102 (the total movement amount of the beam center axis in the X direction) is Y The amplitude is substantially equal to the movement amount of the beam center axis (movement amount of the beam center axis in the Y direction) by the direction scanning electromagnet 103, and the phase is shifted by 90 °. As a result, the beam center axis is controlled so as to draw a circular locus on the irradiation surface of the irradiation target P.
[0050]
At this time, since the two X-direction scanning electromagnets 101 and 102 are connected in series to the X-direction scanning power supply 105 as described above, the beam center axis movement by the downstream X-direction scanning electromagnet 102 is performed. The amplitude of the amount is slightly larger (for example, 1.2 times) than the amplitude of the beam center axis movement amount by the Y-direction scanning electromagnet 103, and the amplitude of the beam center axis movement amount by the upstream X-direction scanning electromagnet 101 is always the above. A proportional relationship (for example, 0.2 times) is maintained in the direction opposite to the amplitude of the beam center axis movement amount of the X-direction scanning electromagnet 102. In this way, a relationship is established in which the total amount of movement of the beam center axis in the X direction and the amount of movement of the beam center axis in the Y direction are substantially equal to each other.
[0051]
FIG. 1 is an explanatory diagram showing a passing behavior of a charged particle beam realized by the above excitation control, and schematically shows a beam axis passing range and a beam passing range in the X-direction scanning plane of the beam. is there. Note that only the magnetic pole regions of the scanning electromagnets 101, 102, and 103 are also shown. At this time, the dashed line m is the center of the beam passage range, and the center axis of the beam coincides with the dashed line m when the deflection amount by all the scanning electromagnets is zero. 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 which 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 displaced by being bent by the X-direction scanning electromagnet 101 on the most upstream side. As a result, the scanning amplitude (in other words, in a certain unit of time) In consideration of the beam axis passing range and the beam diameter as viewed, the beam passing range, the same applies hereinafter) gradually increases toward the downstream. Thereafter, the beam is deflected by the X-direction scanning electromagnet 102 disposed on the downstream side with a relatively large amplitude so that the deviation of the beam position is reduced (in a direction in which the beam passage range is reduced). As a result, the scanning amplitude becomes smaller again downstream of the X-direction scanning electromagnet 102.
[0053]
At this time, since the amount of deflection by the two X-direction scanning electromagnets 101 and 102 is maintained in a proportional relationship as described above, a focal point where the amplitude of the beam center axis becomes 0 is formed, and this focal position Q is effectively reduced. 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 increases again downstream thereof. As the ratio between the deflection amounts of the two X-direction scanning electromagnets 101 and 102 maintained in a proportional relationship as described above decreases, the X-direction scanning point (focal position) Q moves further downstream. In this example, the ratio of the amount of deflection is adjusted by, for example, appropriately selecting the magnetic pole length and the number of coil turns in the beam traveling direction of the electromagnet, so that the scanning point Q is substantially in the horizontal direction of the Y-direction scanning electromagnet 103 as shown in FIG. It is preset so as to come to the center (or at least in the vicinity thereof). The interval between the magnetic poles of the Y-direction scanning electromagnet 103 is set to be as small as possible as long as it does not interfere with the beam passage range.
[0054]
The beam deflected by each of the scanning electromagnets 101, 102, and 103 as described above and whose scanning amplitude gradually increases from the scanning point Q in the Y-direction scanning electromagnet 103 is further downstream of the Y-direction scanning electromagnet 103. The light enters the scatterer 104 and is scattered by the scatterer provided on the scatterer 104. As a result, the distribution of particles constituting the beam in the XY plane spreads in a Gaussian manner around the beam center axis, and the beam intensity distribution spreads downstream. That is, the beam passage range is further expanded (see FIG. 1). At this time, the beam intensity distribution at the irradiation surface position is substantially a two-dimensional Gaussian distribution in the XY directions, and its standard deviation is adjusted to about two-thirds of the radius of the circle drawn by the beam central axis. As a result, 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 area around the scanning center and about 70% of the scanning circle. .
[0055]
The beam emitted from the scatterer 104 passes through the ridge filter 5a, the energy of which is attenuated at a predetermined ratio, and the energy of the beam is given a distribution according to the thickness of the affected part. Thereafter, the dose of the beam is measured by the dose monitor 5b (the integrated passing amount or the intensity distribution may be measured. Based on these values, the dose absorbed by the irradiation target P is controlled) and further input to the bolus 5c. Thus, the energy distribution according to the shape of the lower part of the affected part is obtained (in other words, the dose distribution in the depth direction within the irradiation target P is adjusted). Then, after being formed into a horizontal shape of the affected part by the collimator 5d (in other words, the horizontal dose distribution in the irradiation target P is adjusted), the irradiation target (the affected part of the patient) P is irradiated.
[0056]
In the above, the X-direction scanning electromagnet 101 constitutes the first variable deflection means for deflecting the amount of deflection of the incident charged particle beam in the X direction variably, as described in each claim. Constitutes 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; The scanning electromagnet 103 is provided downstream of the second variable deflecting means, and constitutes a third variable deflecting means for deflecting the charged particle beam deflected by the second variable deflecting means variably in the Y direction. I do.
[0057]
Further, the X-direction scanning power supply 107 constitutes a single excitation power supply common to the first scanning electromagnet and the second scanning electromagnet, and a predetermined amount of deflection between the first scanning electromagnet and the second scanning electromagnet. First deflection control means for controlling the first and second scanning electromagnets is also configured so as to maintain the proportional relationship, and furthermore, the deflection amount by the first variable deflection means and the deflection amount by the second variable deflection means are controlled. In order to maintain a predetermined proportional relationship, and so that the scanning point of the charged particle beam after passing through the second variable deflecting means is located at the center of the third variable deflecting means or at least in the vicinity thereof, It also constitutes a second deflection control means for controlling the second variable deflection means.
[0058]
Next, the operation and effect of the present embodiment will be described.
[0059]
(1) Miniaturization of other beam deflecting means (deflecting electromagnet, quadrupole electromagnet)
As described above, in the charged particle irradiation apparatus 1 of the present embodiment, the beam is bent in the X direction by the X-direction scanning electromagnet 101 on the most upstream side to shift the position (to increase the beam passage range). After that, the beam is deflected by the downstream X-direction scanning electromagnet 102 in the X direction so as to reduce the displacement of the beam in the X direction (to reduce the beam passage range), so that the beam is further deflected inside the Y-direction scanning electromagnet 103. The beam scanning point Q is located. As a result, the X-direction beam passage range of the Y-direction scanning electromagnet 103 is reduced, and after the scanning point Q, the beam axis passes through the Y-direction scanning electromagnet 103 and expands again in the X direction to have a predetermined size. The particle beam is introduced into the collimator 5d.
[0060]
As described above, unlike the conventional structure (Japanese Patent Laid-Open No. 10-282300) using a bending electromagnet or a quadrupole electromagnet which does not have a beam converging function, the X-direction scanning electromagnet 102 having a high beam converging function has a beam passing range in the X direction. Is sharply reduced, so that the beam can be bent once by the X-direction scanning electromagnet 101 to shift its position, and then the transport distance can be reduced while reducing the shift in the position of the beam. The maximum value can be reduced. This makes it possible to reduce the size (reduction in the dimension in the X direction) of the deflecting electromagnet 2C as another deflecting means provided in the transport path as compared with the above-described conventional structure. Further, as a result, the deflection of the support structure (the rotating 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 lowering.
[0061]
(2) Cost reduction
This operation 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 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. 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, and respectively correspond to FIGS. 2 and 1 described above. It is. In FIGS. 5 and 6, parts equivalent to those of the charged particle irradiation apparatus 1 according to the above-described embodiment are denoted by reference numerals with “′” added as a suffix, and description thereof is omitted as appropriate.
[0063]
5 and 6, in the charged particle irradiation apparatus 1 'of this comparative example, only two scanning electromagnets, an X-direction scanning electromagnet 102' and a Y-direction scanning electromagnet 103 ', are vertically adjacently arranged in this order. 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 in the irradiation method of the charged particle irradiation apparatus 1 of the above embodiment, and the center axis of the beam draws a circular locus on the irradiation surface. That is, there is a scanning point Q 'in the X direction at the center (or at least in the vicinity) of the X-direction scanning electromagnet 102' on the upstream side in the horizontal direction, and the scanning amplitude increases toward the downstream side from the scanning point Q '. . Accordingly, 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 poles of the Y-direction scanning electromagnet 103 'in the X direction are inevitable. The spacing also increases.
[0065]
At this time, since the power consumption of the scanning electromagnet is generally proportional to, for example, the square of the magnetic pole interval in the magnetic field generation direction, in this comparative example, the power consumption of the Y-direction scanning electromagnet 103 ′ is For example, it reaches about five times. Therefore, the total power consumption of the two X-direction scanning electromagnets 102 'and two Y-direction scanning electromagnets 103' is significantly increased.
[0066]
Further, regarding the power supply capacity, since the power supply capacity of the scanning electromagnet is generally proportional to, for example, the magnetic pole interval in the magnetic field generation direction, the power supply capacity required for the Y-direction scanning electromagnet power supply 107 ′ for exciting the Y-direction scanning electromagnet 103 ′ is provided. Is, for example, about several times (3 to 5 times) the power of the X-direction scanning electromagnet power supply 105 'for exciting the X-direction scanning electromagnet 102'. For this reason, a particularly large power supply is required for the Y-direction scanning electromagnet power supply 107 ′. In some cases, the power supply is not available in a normal market and needs to be manufactured separately, which increases the equipment cost (initial cost).
[0067]
On the other hand, in the charged particle irradiation device 1 of the present embodiment, the X-direction scanning electromagnet 101 and the X-direction scanning electromagnet The number of the scanning electromagnets 102 and the Y-direction scanning electromagnets 103 is increased by one in total of three. However, 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 magnetic pole interval is reduced by reducing the X-direction beam passage range of the most downstream Y-direction scanning electromagnet 103. It was found that the size of the Y-directional scanning electromagnet 103 'of the comparative example can be reduced to, for example, about 1/2. As a result, the power consumption of the Y-direction scanning electromagnet 103 can be reduced to about 1/3 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 when compared with the comparative example, has only 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. The sum 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 by the two of the X-direction scanning electromagnet 102 'and the Y-direction scanning electromagnet 103' in the comparative example. For example, the power consumption can be reduced to about 1/2 of the total power consumption, and the operating cost (running cost) can be reduced.
[0068]
As for the power supply 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 described. Since the magnetic pole interval is reduced by the reduction, the power supply capacity of the Y-direction scanning power supply 107 can be reduced to about 60% of the excitation power supply 107 'of the Y-direction scanning electromagnet 103' of the comparative example, and the cost is 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 deflection amount and is extremely small, the power supply capacity to be increased for the X-direction scanning electromagnet is different from the comparative example. About ３ of the power supply capacity of the X-direction scanning power supply 107 ′ in the example is sufficient. Regarding the power supply capacity used for the X-direction scanning electromagnet 102, the beam passage 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 extend the effective magnetic field range of the scanning magnet magnetic field. However, in this case, since the extension is in the direction (X direction) parallel to the magnetic pole surface, the increase in the power supply capacity is not so large as when the magnetic pole interval is increased, and is largely different from the X direction scanning power supply 107 'of the comparative example. Not enough is enough. As a result, when viewed comprehensively, the equipment cost (initial cost) required for the power supplies 105 and 107 used for exciting the three scanning electromagnets 101, 102 and 102 is reduced by the two scanning electromagnets 102 of the comparative example. It has been found that the equipment costs required for the power sources 105 and 107 used for exciting the '′ and 103' can be at least substantially equal to or smaller than the equipment costs.
[0069]
As described above, in the charged particle irradiation apparatus 1 of the present embodiment, the operation cost (running cost) is reduced as compared with the comparative example including one X-direction scanning electromagnet and one Y-direction scanning electromagnet. And equipment costs can be at least approximately equal or less. Therefore, in total, the cost can be reduced more reliably than in the comparative example.
[0070]
(3) Other
(1) Effect of sharing the X-direction scanning power supply
As described above, in the present invention, it is necessary to maintain a predetermined proportional relationship between the amount of deflection by the X-direction scanning electromagnet 101 and the amount of deflection by the X-direction scanning electromagnet 102. In the present embodiment, since the two X-direction scanning electromagnets 101 and 102 are connected in series to a common X-direction scanning power supply 105, the amount of beam deflection by the respective scanning electromagnets 101 and 102 is particularly adjusted. Even without doing so, a proportional relationship can be easily obtained. Therefore, the operation can be simplified, and the possibility of erroneous irradiation due to the deviation can be reduced.
[0071]
(2) Effect of scatterer position
In general, in the lateral beam expansion method that combines beam scanning and beam diameter expansion, the quality of an irradiation beam reaching an irradiation target deteriorates as the scatterer and the beam scanning position are farther apart. For example, when two scanning electromagnets are used, if a scattered object is arranged upstream or downstream of the scanning electromagnets, one of the scanning electromagnets will be farther from the scattered object, and the angular distribution of the irradiation beam will be increased. When the beam is cut out by the collimator (1), the cut (hemi-shadow) 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 reduced as compared with the comparative example of FIG. Can be reduced. Thereby, the spread of the beam angle distribution at the irradiation surface position of the irradiation target P can be reduced, so that when the beam is cut out in the horizontal direction by the collimator 5d, the transverse beam intensity distribution is cut off (= half of the dose distribution in the irradiation target). (Shadow) can be reduced, and the irradiation accuracy can be improved. In addition, an irradiation device 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 at the center of the Y-direction scanning magnet 103 but at or near the center of the scatterer 104. Can also be adjusted. In this case, although the gap between the magnetic poles 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 embodiment, the scatterer 104 is disposed downstream of the Y-direction scanning electromagnet 103, which is the most downstream side. However, the present invention is not limited to this. It may be provided between them. Hereinafter, this modified example will be described with reference to FIGS. 7 and 8.
[0074]
FIG. 7 is a diagram schematically illustrating a beam axis passing range and a beam passing range in the X-direction scanning plane of the charged particle irradiation apparatus according to the present modification, and is a diagram corresponding to FIG. 1 of the above embodiment. In FIG. 7, the same parts as those of the charged particle irradiation apparatus 1 according to the above embodiment are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.
[0075]
7, in the charged particle device of this modified example, the scatterer 104 is arranged 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). And 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 in the irradiation method of the charged particle irradiation apparatus 1 of the above embodiment. At this time, the scatterer 104 scatters the particles between the X-direction scanning electromagnet 102 and the Y-direction scanning electromagnet 103, and the distribution of the particles constituting the beam in the XY plane spreads in a Gaussian manner around the beam central axis, and is downstream. The beam intensity distribution expands as it proceeds. Finally, the beam center axis draws a circular locus on the irradiation surface of the irradiation target P.
[0077]
Also in the present modification, similar to the above-described embodiment, the basic effects of the present invention (1) downsizing of other beam deflecting means and (2) effects of cost reduction can be obtained.
[0078]
That is, after the beam is bent in the X direction by the X-direction scanning electromagnet 101 on the most upstream side and deflected to shift the position, the displacement of the beam position in the X direction is reduced by the X-direction scanning electromagnet 102 on the downstream side. The beam is deflected and the beam scanning point Q is positioned inside the Y-direction scanning electromagnet 103 on the downstream side via the scatterer 4, thereby reducing the X-direction beam passing range in the Y-direction scanning electromagnet 103. Accordingly, the size of the bending electromagnet 2C can be reduced as compared with a conventional structure using a bending electromagnet or a quadrupole electromagnet which does not originally have a beam converging function that much. In addition, this makes it possible to reduce the operating cost and the equipment cost to be at least substantially equal to or smaller than the original structure including one X-direction scanning electromagnet and one Y-direction scanning electromagnet, The cost can be reduced as a whole.
[0079]
Since the scatterer unit is located 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-described embodiment. Almost the same effects as in the above embodiment can be obtained. In particular, for example, when compared with a conventional charged particle beam irradiation apparatus (for example, Japanese Patent Application Laid-Open No. 10-212292) on the premise that the scatterer is located between the X-direction scanning electromagnet and the Y-direction scanning electromagnet, The effect is remarkable.
[0080]
FIG. 8 shows a charged particle irradiation apparatus according to a comparative example of this embodiment, which is substantially equivalent to the charged particle irradiation apparatus according to the above-mentioned Japanese Patent Application Laid-Open No. 10-212292 having one X-direction scanning electromagnet and one Y-direction scanning electromagnet. 1 schematically shows a beam axis passing range and a beam passing range of the beam in the X-direction scanning plane. In FIG. 8, portions equivalent to those of the charged particle irradiation apparatus 1 according to the above embodiment are denoted by reference numerals with "" added as a suffix, and description thereof will be omitted as appropriate.
[0081]
8, in the charged particle irradiation apparatus of this comparative example, only two scanning electromagnets, an X-direction scanning electromagnet 102 ″ and a Y-direction scanning electromagnet 103 ″, are arranged vertically close to each other in this order. A scatterer 104 "is disposed between the electromagnet 103" and the electromagnet 103 ". In this case, similarly to the comparative example described above with reference to FIG. There is a scanning point Q ", and the scanning amplitude increases toward the downstream side. However, the scanning amplitude is further increased by the scatterer 104" before entering the Y-direction scanning electromagnet 103 ". Thereby, the Y-direction scanning is performed. The beam passing range in the X direction at the position of the electromagnet 103 ″ becomes considerably large, and the magnetic pole interval in the X direction of the Y direction scanning electromagnet 103 ″ becomes considerably large.
[0082]
On the other hand, in the charged particle irradiation apparatus of the present modification shown in FIG. 7, as can be seen from comparison with FIG. The distance can be greatly reduced as compared with the Y-direction scanning electromagnet 103 ″ of the comparative example. It can be seen that the effects described in the above (1) and (2) can be obtained. Even when it is assumed that the Y-direction scanning electromagnet 103 is disposed between the electromagnet 102 and the Y-direction scanning electromagnet 103, the distance between the magnetic poles of the Y-direction scanning electromagnet 103 can be reduced, and the effect of cost reduction and miniaturization of other deflection means can be obtained. Can be planned.
[0083]
In addition, the present modification has the following effects in addition to the above.
[0084]
That is, as can be seen by comparing FIG. 7 and FIG. 1, in the present modification, the distance between the scatterer 104 and the irradiation surface is larger than in the embodiment shown in FIG. This reduces the amount of scattering required to form the same beam intensity distribution on the irradiation surface, so that 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 decreases, and the energy of the beam reaching the irradiation surface increases. Therefore, the reaching depth of the beam in the irradiation target P becomes deep, and irradiation can be performed on a target deeper than in the above embodiment.
[0085]
In the above description, 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 scatterer is not essential. It goes without saying that the effects (1) and (2) inherent in the invention described above can be obtained regardless of the presence or absence of the body 104.
[0086]
Further, the case where the two X-direction scanning electromagnets 101 and 102 are excited by the single X-direction scanning power supply 105 has been described above as an example, but the present invention is not limited thereto. , 102 may be separate (a first excitation power supply for exciting the X-direction scanning electromagnet 101 as the first operation electromagnet and a second excitation power supply 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, whereby the scanning point position can be adjusted as desired. Therefore, even when there is a change in equipment conditions between the X-direction scanning electromagnet 101 and the X-direction scanning electromagnet 102 and a magnet design error, the scanning point can be adjusted so as not to shift, and the beam can be adjusted in the Y-direction. It is possible to avoid collision with the magnetic pole of the scanning electromagnet 103 and maintain irradiation accuracy. At this time, if the respective power supplies are controlled by a common power supply control means (single signal source), it is not necessary to adjust the phases of the two X-direction scanning electromagnets 101 and 102, so that the operation is simplified. In addition, the possibility of erroneous irradiation due to a phase shift can be reduced.
[0087]
Further, the case where the scanning is performed so that the beam center trajectory is circular on the irradiation surface has been described above as an example. However, the present invention is not limited to this, and an arbitrary trajectory may be drawn, for example, by scanning like a television. Also in this case, by setting the beam deflection amounts of the two X-direction scanning electromagnets 101 and 102 to be in a proportional relationship, the X-direction scanning point position Q does not change, and the same effect as that of the present embodiment can be obtained.
[0088]
Furthermore, the above description has been made by taking as an example the case where the present invention is applied to a rotating gantry that changes the irradiation direction by rotating the irradiation device.However, the present invention is not limited to this. Can be applied. In this case, generally, no device for deflecting the beam is provided between the X-direction scanning electromagnets 101 and 102, but the same effect as in the present embodiment can be obtained.
[0089]
【The invention's effect】
According to the present invention, the second scanning electromagnet having a high beam convergence function is used to sharply deflect the beam in the X direction so as to reduce the displacement of the beam position. Therefore, the beam is temporarily bent by the first scanning electromagnet to shift the position. After the deflection, the maximum value of the beam passage range when the beam is deflected so as to reduce the deviation of the beam position 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 usually provided between them. Further, the total power consumption of the three first to third scanning electromagnets is reduced to, for example, about one half of the total power consumption of the original two X-direction and Y-direction scanning electromagnets to reduce the operating cost (running cost). ) Can be reduced, and the equipment cost (initial cost) required for the excitation power supply of the first to third scanning electromagnets can be reduced by the equipment required for the original excitation power supply of the two X-direction and Y-direction scanning electromagnets. Since the cost 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 the overall schematic structure of a charged particle irradiation apparatus according to one embodiment of the present invention.
FIG. 3 is a diagram illustrating an example of a temporal change of an excitation current supplied to the X-direction scanning electromagnet and the Y-direction scanning electromagnet by the X-direction scanning electromagnet power supply and the Y-direction scanning electromagnet power supply.
FIG. 4 is a diagram illustrating an example of a temporal change of a movement amount of a beam center axis on an irradiation surface due to 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 having 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 the 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 in the X-direction scanning plane of a beam of a charged particle irradiation apparatus according to a comparative example having one X-direction scanning electromagnet and one Y-direction scanning electromagnet. 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
107 X-direction scanning power supply (single excitation power supply, first deflection control means, second deflection control means)
P Irradiation target (affected area)

Claims (8)

In a medical charged particle irradiation device that irradiates the affected part of a patient with charged particles,
A first scanning electromagnet that deflects the 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;
A second scanning electromagnet provided downstream of the first scanning electromagnet and deflecting the charged particle beam deflected by the first scanning electromagnet in the one direction so as to reduce the displacement of the beam position; ,
The charged particle beam provided on the downstream side of the second scanning electromagnet and deflected by the second scanning electromagnet is deflected to another direction orthogonal to the one direction in a plane perpendicular to the beam traveling direction. A medical charged particle irradiation apparatus, comprising: a third scanning electromagnet. In a medical charged particle irradiation device that irradiates the affected part of a patient with charged particles,
A first scanning electromagnet that deflects the 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;
A second scanning electromagnet provided downstream of the first scanning electromagnet and deflecting the charged particle beam deflected by the first scanning electromagnet in the one direction so as to reduce the displacement of the beam position; ,
The charged particle beam provided on the downstream side of the second scanning electromagnet and deflected by the second scanning electromagnet is deflected to another direction orthogonal to the one direction in a plane perpendicular to the beam traveling direction. A third scanning electromagnet;
First deflection control means for controlling the first and second scanning electromagnets so as to maintain a predetermined proportional relationship between the deflection amount of the first scanning electromagnet and the deflection amount of the second scanning electromagnet. Characterized medical particle irradiation equipment. The medical charged particle irradiation apparatus according to claim 1 or 2, further comprising a scatterer for scattering a charged particle beam downstream of the third scanning electromagnet. The medical charged particle irradiation apparatus according to claim 1, wherein a scatterer for scattering 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 means includes a single excitation power supply common to the first scanning electromagnet and the second scanning electromagnet, and the first scanning electromagnet and the second scanning electromagnet. A medical charged particle irradiation apparatus, wherein each of the scanning electromagnets is connected in series to the single excitation power supply. 3. The medical charged particle irradiation apparatus according to claim 2, wherein the first deflection control means includes a first excitation power supply and a second excitation power supply for supplying power to the first scanning electromagnet and the second scanning electromagnet, respectively. A medical charged particle irradiation apparatus, comprising: a power supply control unit common to the first and second excitation power supplies. In a medical charged particle irradiation device that irradiates the affected part of a patient with charged particles,
A first scanning electromagnet for deflecting the incident charged particle beam in one direction in a plane perpendicular to the beam traveling direction;
A second scanning electromagnet provided downstream of the first scanning electromagnet and deflecting the charged particle beam deflected by the first scanning electromagnet in the one direction;
The charged particle beam provided on the downstream side of the second scanning electromagnet and deflected by the second scanning electromagnet is deflected to another direction orthogonal to the one direction in a plane perpendicular to the beam traveling direction. A medical charged particle irradiation apparatus, comprising: a third scanning electromagnet. In a medical charged particle irradiation device that irradiates the affected part of a patient with charged particles,
First variable deflection means for deflecting the amount of deflection of the incident charged particle beam in the X direction variably;
A second variable deflecting means provided downstream of the first variable deflecting means and variably deflecting the amount of deflection of the charged particle beam deflected by the first variable deflecting means in the X direction;
A third variable deflecting means provided downstream of the second variable deflecting means and variably deflecting the amount of deflection of the charged particle beam deflected by the second variable deflecting means in the Y direction;
Scanning of the charged particle beam so as to maintain a predetermined proportional relationship between the amount of deflection by the first variable deflection unit and the amount of deflection by the second variable deflection unit, and after passing through the second variable deflection unit A second deflection control means for controlling the first and second variable deflection means so that a point is at or near the center of the third variable deflection means; apparatus.

Images