JP2019180654A - Convergent electromagnet and charged particle beam irradiation device - Google Patents

Abstract

To provide a convergent electromagnet that deflects a charged particle beam incident from a large angular range, and converges it in an isocenter.SOLUTION: A convergent electromagnet of the present invention is provided as follows: the convergent electromagnet includes coil pairs arranged to sandwich a path of a charged particle beam; the coil pairs generates an effective magnetic field region where a magnetic field is directed in the direction (Z-axis) perpendicular to the traveling direction (X-axis) of the charged particle beam, and performs deflection by a deflection angle φ to the X-axis in a deflection starting point Q in the XY surface; the incident charged particle beam is deflected by the effective magnetic field region, and is applied to an isocenter by an irradiation angle θ to the X-axis; any point P2 on the boundary of an emission side of the effective magnetic field region is present in a position of equal distance rfrom the isocenter; the point P1 and the point P2 on the boundary of the incident side of the effective magnetic field region are present on the circular arc of a radius rand a central angle θ+φ; and a distance R between the deflection starting point Q and the point P1 satisfies a relational expression (4) where the distance between the deflection starting point Q and the isocenter is assumed L.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a focusing electromagnet and a charged particle beam irradiation apparatus using the focusing electromagnet.

  Conventionally, particle beam therapy for irradiating a malignant tumor such as cancer with a charged particle beam accelerated to high energy to treat the malignant tumor has been performed.

  When an object is irradiated with a charged particle beam, energy (dose) is applied to the object along the path of the charged particle beam in the object. When concentrating a dose on a limited area (target) inside an object, the concentration of the dose can be improved by irradiating the charged particle beam from various directions so that the charged particle beam overlaps the target. Done.

  In the field of particle beam therapy, a method of irradiating a charged particle beam from a plurality of directions is generally used in order to give a large dose to a target in the body while suppressing normal tissue exposure. As a device for irradiating a target with a charged particle beam from a plurality of directions, a device is known in which a plurality of fixed irradiation ports are provided in a treatment room and a device for changing the characteristics of the charged particle beam is shared by the plurality of fixed irradiation ports. (Patent Document 1). Further, by rotating the target itself, a device that irradiates the target with a charged particle beam emitted from one fixed irradiation port from a plurality of directions (Patent Document 2), or a rotation that rotates the entire charged particle beam transport device. An irradiation apparatus (Patent Document 3) is also known.

JP 2002-113118 A Japanese Patent Laid-Open No. 60-20439 Japanese Patent No. 2836446

  In the method described in Patent Document 1, the number of directions in which a target is irradiated with a charged particle beam is the same as the number of fixed irradiation ports, and the direction in which the target is irradiated with a charged particle beam (irradiation angle) is not continuous. Absent. In addition, as many transport lines for charged particle beams as the number of irradiation directions are required, and there are problems in terms of manufacturing cost and installation space. In the method described in Patent Document 2, since the target is irradiated with the charged particle beam from various directions by rotating the patient, the load on the rotating patient is large, and the tumor (target) caused by the rotation There is a problem that deformation is likely to occur. In the method described in Patent Document 3, while a charged particle beam can be continuously irradiated onto a target, a huge mechanism for integrally rotating a charged particle beam transport line and an irradiation port is required. There is also a problem in terms of the cost of manufacturing such a mechanism and the installation space.

  In view of such circumstances, an object of the present invention is to provide a converging electromagnet that deflects a charged particle beam incident from a wide angle range and converges it to an isocenter, and a charged particle beam irradiation apparatus using the same.

The present invention includes the following embodiments [1] to [11].
[1]
A focusing electromagnet having a coil pair arranged so as to sandwich a path of a charged particle beam,
The coil pair is configured to generate an effective magnetic field region in which a magnetic field is directed in a direction (Z axis) orthogonal to a traveling direction (X axis) of a charged particle beam when current is input. The axis perpendicular to both the Z axis and the Y axis is the Y axis,
In the XY plane,
The charged particle beam deflected by the deflection angle φ with respect to the X axis at the deflection start point Q and incident on the effective magnetic field region is deflected by the effective magnetic field region, and is irradiated to the isocenter at an irradiation angle θ with respect to the X axis.
An arbitrary point P2 on the boundary of the effective magnetic field region on the emission side of the charged particle beam is located at an equal distance r ₁ from the isocenter,
The point P2 and the point P1 on the boundary of the entrance side of the charged particle beam of the effective magnetic field region is in a circular arc on a radius r ₂ and the central angle (theta + phi),
The distance R between the deflection starting point Q and the point P1 is represented by the relational expression (4), where L is the distance between the deflection starting point Q and the isocenter.
Satisfying the converging electromagnet.
[2]
The convergence electromagnet includes two or more pairs of the coil pairs,
The two or more pairs of coils are arranged so as to sandwich the path of the charged particle beam and line up in the Y-axis direction,
A current switch is connected to the first coil pair and the second coil pair among the two or more coil pairs,
The current switch is configured to supply current to any one of the first coil pair and the second coil pair;
[1] The focusing electromagnet according to [1], wherein the first coil pair and the second coil pair are configured such that directions of magnetic fields in an effective magnetic field region to be generated are opposite to each other.
[3]
The converging electromagnet according to [1] or [2], wherein the deflection starting point Q and the isocenter are on the X axis.
[4]
An accelerator that generates a charged particle beam;
A distributed electromagnet device that deflects the charged particle beam from the accelerator at a deflection angle φ of 10 degrees or more at the deflection start point Q; and the focusing electromagnet according to any one of [1] to [3];
A power supply for supplying and exciting current to the converging electromagnet;
A charged particle beam irradiation apparatus.
[5]
A vacuum duct connecting the distribution electromagnet device and the converging electromagnet;
The vacuum duct has a fan shape on the XY plane, and is configured so that even a charged particle beam deflected at a deflection angle φ of 10 degrees or more can pass through the vacuum duct. ] The charged particle beam irradiation apparatus of description.
[6]
A driving device for rotating the focusing electromagnet around the X axis at a rotation angle ω;
Further comprising
The charged particle beam irradiation apparatus according to [4] or [5], wherein the charged particle beam is irradiated to the isocenter from an arbitrary combination range of the rotation angle ω and the irradiation angle θ.
[7]
The converging electromagnet is configured so that the longitudinal direction of the converging electromagnet can be inclined with respect to a floor surface of an irradiation chamber in which the charged particle beam irradiation apparatus is installed, [4] to [6] The charged particle beam irradiation apparatus of any one of Claims.
[8]
The charged particle beam irradiation apparatus according to any one of [4] to [7], further including a quadrupole electromagnet provided on an upstream side of the sorting electromagnet apparatus and configured to adjust a beam shape of the charged particle beam.
[9]
The charged particle beam irradiation apparatus according to [8], wherein the excitation current of the quadrupole electromagnet is controlled for each irradiation angle θ in order to adjust the beam shape of the charged particle beam for each irradiation angle θ.
[10]
A steering electromagnet device provided upstream of the distribution electromagnet device;
A beam monitor device provided on the exit side of the focusing electromagnet;
[4] to [9] feedback control of at least one exciting current of the sorting electromagnet device, the converging electromagnet, and the steering electromagnet from information on the beam position of the charged particle beam from the beam monitor device The charged particle beam irradiation apparatus according to any one of the above.
[11]
It further has an image capturing device provided so as to sandwich the target in the isocenter,
The image capturing device according to any one of [4] to [10], wherein the image capturing device is configured to generate image information of the target before or during irradiation of the target with a charged particle beam. Charged particle beam irradiation device.

  The focusing electromagnet according to one embodiment of the present invention can continuously make a direction (irradiation angle θ) in which a target is irradiated with a charged particle beam. The focusing electromagnet can focus the charged particle beam on the target even if the charged particle beam is incident from a wide angle range (for example, ± 10 degrees to less than ± 90 degrees). By using the focusing electromagnet 10, it is not necessary to move the target (patient), and the deformation of the target accompanying the load and movement on the patient can be prevented or reduced. In the converging electromagnet 10, the effective magnetic field region 15 is formed so that the irradiation angle θ is determined so that the charged particle beam converges on the target in accordance with the deflection angle φ, so that the converging electromagnet is physically moved. Therefore, the problem of manufacturing cost and installation space can be reduced by that amount.

It is a schematic block diagram of the convergence electromagnet which concerns on one Embodiment. It is a figure for demonstrating formation of the effective magnetic field area | region which concerns on one Embodiment. It is a schematic block diagram of the power supply device which concerns on one Embodiment. It is a schematic block diagram of the charged particle beam irradiation apparatus which concerns on one Embodiment. It is a schematic block diagram of the charged particle beam irradiation apparatus which concerns on one Embodiment. It is a schematic block diagram of the charged particle beam irradiation apparatus which concerns on one Embodiment. It is a schematic block diagram of the charged particle beam irradiation apparatus which concerns on one Embodiment. It is a schematic block diagram of the charged particle beam irradiation apparatus which concerns on one Embodiment. It is a schematic block diagram of the charged particle beam irradiation apparatus which concerns on one Embodiment.

[First Embodiment]
The first embodiment of the present invention relates to a converging electromagnet 10 that deflects a charged particle beam incident from a wide angle range and converges it to an isocenter.

  FIG. 1A is a schematic configuration diagram of a converging electromagnet 10 according to the present embodiment. The traveling direction of the charged particle beam is the X axis, the direction of the magnetic field generated by the focusing electromagnet 10 is the Z axis, and the direction orthogonal to the X axis and the Z axis is the Y axis. The converging electromagnet 10 is configured to converge a charged particle beam incident from a wide range of a deflection angle φ with respect to the X axis on the XY plane to the isocenter O.

  In this embodiment, as shown in FIG. 2, the isocenter O is the origin of the XYZ space and the upstream side (accelerator side) is the positive direction of the X axis, but this is not limitative. The range of the deflection angle φ is in the range of more than −90 degrees to less than +90 degrees, and the plus (+ Y axis direction) deflection angle range and the minus (−Y axis direction) deflection angle range may be different (asymmetrical). ). For example, the maximum positive deflection angle (φ = φmax) may be 45 degrees, and the maximum negative deflection angle (φ = −φmax) may be −30 degrees.

  The converging electromagnet 10 includes one or more pairs of coils, and the coil pairs are oriented in a direction (Z-axis direction in the figure) perpendicular to the traveling direction of the charged particle beam and the spreading direction of the deflection angle φ of the charged particle beam. A uniform magnetic field is generated (effective magnetic field regions 15a and 15b), and arranged so as to sandwich the path of the charged particle beam. The effective magnetic field region generated by one pair of coils of the focusing electromagnet 10 has a crescent-like shape on the XY plane as shown in FIG. 1A, and details thereof will be described later. Note that the gap between the opposing coil pairs through which the charged particle beam passes (distance in the Z-axis direction) is sufficiently smaller than the range in which the charged particle beam spreads on the XY plane. We do not consider the spread of direction.

  FIG. 1B is a cross-sectional view of the focusing electromagnet 10 taken along the line AA. In the present embodiment, the focusing electromagnet 10 preferably includes at least two sets of coil pairs 11a and 11b. Magnetic poles 12a and 12b are incorporated in the coils 11a and 11b, respectively, and a yoke 13 is connected to the magnetic poles 12a and 12b. A power supply device (FIG. 3) described later is connected to the converging electromagnet 10. By supplying current (also referred to as excitation current) to the coil pairs 11a and 11b from the power supply device, the converging electromagnet 10 is excited and effective magnetic field regions 15a and 15b are formed. Note that the range of the effective magnetic field region 15a and the range of the effective magnetic field region 15b may be different (asymmetric). For example, if the plus (+ Y-axis direction) deflection angle range and the minus (-Y-axis direction) deflection angle range are asymmetric, the effective magnetic field regions 15a and 15b are formed asymmetrically accordingly, and are not used effectively. The magnetic field region can be reduced.

  The range of the deflection angle φ of the charged particle beam deflected by the sorting electromagnet device 20 and incident on the converging electromagnet 10 ranges from the maximum positive deflection angle (φ = φmax) to the maximum negative deflection angle (φ = −φmax). The positive maximum deflection angle φmax is an angle between 10 degrees and less than 90 degrees, and the negative maximum deflection angle −φmax is an angle greater than −90 degrees and −10 degrees or less. A deflection angle φ and an irradiation angle θ described later are the angles of the path of the charged particle beam with respect to the X axis on the XY plane.

  The charged particle beam incident in the positive deflection angle range (φ = 0 to φmax) is deflected by the effective magnetic field region 15a of the first coil pair 11a and irradiated to the isocenter O. The charged particle beam incident in the negative deflection angle range (less than φ = 0 to −φmax) is deflected by the effective magnetic field region 15b of the second coil pair 11b and irradiated to the isocenter O. The directions of the effective magnetic field region 15a and the effective magnetic field region 15b are opposite to each other. The charged particle beam incident on the converging electromagnet 10 at the deflection angle φ = 0 from the sorting electromagnet apparatus 20 passes through one of the effective magnetic field regions 15a and 15b or between both the regions 15a and 15b, and enters the isocenter O. Converge.

  The deflection angle φ of the charged particle beam incident on the focusing electromagnet 10 is controlled by the sorting electromagnet apparatus 20. The distributed electromagnet device 20 generates a magnetic field directed in a direction (Z axis in the figure) perpendicular to the traveling direction (X axis in the figure) of a charged particle beam supplied from an accelerator (not shown), and passes charged particles. An electromagnet that deflects the beam and a control unit that controls the intensity and direction of the magnetic field (not shown). The distribution electromagnet apparatus 20 controls the intensity and direction (Z-axis direction) of the magnetic field to deflect the charged particle beam on the XY plane, and converges the charged particle beam deflected at the deflection start point Q with the deflection angle φ. 10 is emitted. Here, the deflection starting point Q and the isocenter O are on the X axis.

  A vacuum duct (not shown) is provided between the accelerator and the sorting electromagnet device 20 and between the sorting electromagnet device 20 and the converging electromagnet 10, and the charged particle beam is transported in the middle, thereby Does not attenuate significantly.

  A calculation formula for forming the effective magnetic field region 15a of the converging electromagnet 10 will be described with reference to FIG. Since the deflection of the charged particle beam in the Z-axis direction is not considered, the formation of an effective magnetic field region on the XY plane will be described. Although the effective magnetic field region 15a of the converging electromagnet 10 will be described, the same applies to the effective magnetic field region 15b, and the description thereof will be omitted.

First, the boundary of the effective magnetic field region 15a of the exit side 17 of the charged particle beam focusing electromagnet 10 is determined to be in the range of from isocenter O to the position of equidistant r _1. Next, the boundary of the effective magnetic field region 15a on the incident side 16 of the charged particle beam of the focusing electromagnet 10 is a virtual position located at a predetermined distance L from the isocenter O based on relational expressions (1) to (5) described later. It is determined so that the charged particle beam which is deflected by the deflection angle φ at the upper deflection starting point Q and converges on the isocenter O. Here, the hypothetical deflection starting point Q is a point that is assumed that the charged particle beam receives a kick with a deflection angle φ at an extremely short distance at the center of the sorting electromagnet apparatus 20.

The charged particle beam that has been transported by the deflection angle φ enters from any point P1 on the boundary of the effective magnetic field region 15a on the incident side 16 performs circular motion radius of curvature r ₂ in the effective magnetic field region 15a (at this time The central angle of (2) is (φ + θ).) The light exits from the point P2 on the boundary of the effective magnetic field region 15a on the emission side 17 and is irradiated to the isocenter O. That is, the points P1 and P2 are on a circular arc having a radius r ₂ and the central angle (φ + θ).

Assume an XY coordinate system with the isocenter O as the origin in the XY plane. Assuming that the angle formed by the X axis and the straight line connecting the point P2 on the emission side 17 and the isocenter O is the irradiation angle θ, the coordinates (x, y), the deflection angle φ, and the point Q of the point P1 on the incident side 16 The distance R to the point P1 is obtained from the following relational expressions (1) to (4).

Here, a magnetic field having a uniform magnetic flux density B is generated in the effective magnetic field region 15a. If the momentum of the charged particle beam is p (approximately depending on the accelerator) and the charge is q, the charge deflected in the magnetic field is charged. the radius of curvature r ₂ of the particle beam is represented by the formula (5).

Based on the relational expressions (1) to (5), the shape and arrangement of the coil pair 11a and the magnetic pole 12a of the converging electromagnet 10 are adjusted, and the current flowing through the coil pair 11a is adjusted. The shape can be adjusted. In other words, it bounded so that the distance becomes equidistant r ₁ between any point P2 and the isocenter O on the boundary of the effective magnetic field region 15a of the exit side 17, adjusting the flux density B of the effective magnetic field region 15a Then, r ₂ is determined from the equation (5), and the incident side is set so that the distance R between the point P1 on the boundary of the effective magnetic field region 15a on the incident side 16 and the deflection starting point Q has the relationship of the equation (4). The boundaries of the 16 effective magnetic field regions 15a are defined. The maximum value of φ in Equation (3) is the maximum deflection angle φmax. Although not limited thereto, the deflection start point Q, the focusing electromagnet 10, and the isocenter O so that the charged particle beam passing through the deflection starting point Q converges on the isocenter O without being deflected by the focusing electromagnet 10. It is preferable to adjust the arrangement in order to simplify the apparatus configuration.

  The boundary between the effective magnetic field regions 15a and 15b of the converging electromagnet 10 obtained as described above is an ideal shape for converging the charged particle beam to the isocenter O. Actually, even if there is a deviation from the ideal shape or non-uniformity of the magnetic field distribution, the amount of excitation (magnetic flux density B) of the focusing electromagnet 10 is finely adjusted in advance for each deflection angle φ, and the information is obtained. Can be stored in a power supply device (not shown), and the charged particle beam can be deflected in accordance with the isocenter O by controlling them so that the deflection angle φ and the current amount of the focusing electromagnet 10 are linked. it can. In addition, when the non-uniformity of the magnetic field distribution can be predicted in advance, it is possible to finely adjust the trajectory of the charged particle beam by correcting the shape and arrangement of the coil pair 11a and the magnetic pole 12a of the focusing electromagnet 10. is there.

  FIG. 3 is a schematic configuration diagram of the power supply device 30 that supplies current to the converging electromagnet 10. The power supply device 30 includes a current switch 31 connected to the bus bars 18a and 18b that are current supply ends of the coil pairs 11a and 11b of the converging electromagnet 10, and a power supply 32 that supplies current to the coils 11a and 11b through the power switch 31. And an irradiation angle control unit 33 that controls the current switch 31 and the power source 32.

  Since the charged particle beam basically passes through one of the coil pairs 11a and 11b, the power supply device 30 supplies a current (excitation current) supplied from the power supply 32 to the coil pairs 11a and 11b as a current switch 31. And the current is passed through one of the coil pairs 11a and 11b through which the charged particle beam passes.

  The current switch 31 and the power source 32 are controlled by the irradiation angle control unit 33. Depending on the energy of the charged particle beam and / or the deflection angle φ of the charged particle beam by the distribution magnet device 20, the irradiation angle control unit 33 controls the current flowing through the coil pairs 11a and 11b by controlling the power source 32. By controlling the current switch 31, the coil pair 11 a and 11 b to be supplied with current is switched. The irradiation angle control unit 33 switches the currents to be supplied to the coil pairs 11a and 11b by the current switch 31, so that the number of coil pairs simultaneously connected to the power source 32 is reduced, and the inductance and resistance corresponding to the reduced coil pairs are reduced. Therefore, the power capacity of the power source 32 can be reduced.

  The irradiation angle control unit 33 may perform synchronous control with the deflection direction (deflection angle φ) of the charged particle beam by the sorting electromagnet device 20. Further, the irradiation angle control unit 33 may periodically input information about the deflection angle φ of the charged particle beam from the sorting electromagnet device 20 and control the current switch 31 and the power source 32 based on the information. The energy and excitation amount (current value for each coil pair 11a and 11b) of the charged particle beam corresponding to the deflection angle φ are obtained in advance and stored in the irradiation angle control unit 33 in association with the deflection angle φ. The control unit 33 may control the excitation amount according to the deflection angle φ by referring to it.

  When the amount of current flowing through the coils 11a and 11b may be equal in both the coil pairs 11a and 11b, that is, when the amount of excitation is not changed for each deflection angle φ, the coil pair 11a and the coil pair 11b are connected in series. And a single power source 32 may cause current to flow through both coil pairs 11a and 11b. In this case, the power supply device 30 may not include the current switch 31.

  The focusing electromagnet 10 according to the present embodiment can continuously make a direction (irradiation angle θ) in which a charged particle beam is irradiated onto a target (isocenter O). The converging electromagnet 10 can converge the charged particle beam to the target even if the charged particle beam is incident from a wide angle range (for example, ± 10 degrees to less than 90 degrees). By using the focusing electromagnet 10, it is not necessary to move the target (patient), and the deformation of the target due to the load and movement on the patient can be prevented or reduced as compared with the conventional technique for moving the patient. In the converging electromagnet 10, an effective magnetic field region is formed so that the irradiation angle θ is determined so that the charged particle beam converges on the target in accordance with the deflection angle φ, so that the converging electromagnet can be physically moved. A huge mechanism is not required, and the problem of manufacturing cost and installation space can be reduced accordingly.

[Second Embodiment]
The second embodiment of the present invention relates to a charged particle beam irradiation apparatus 100 using the converging electromagnet 10 according to the first embodiment.

  FIG. 4A is a schematic configuration diagram of the charged particle beam irradiation apparatus 100 according to the present embodiment, and FIG. 4B is a focusing electromagnet 10 on the downstream side from the accelerator 40 on the upstream side of the charged particle beam irradiation apparatus 100. It is a schematic perspective view up to. The charged particle beam irradiation apparatus 100 includes a focusing electromagnet 10, a sorting electromagnet apparatus 20, a power supply apparatus 30, and an accelerator 40. The charged particle beam irradiation apparatus 100 may further include at least one of a beam slit device 50, a quadrupole electromagnet device 52, a steering electromagnet device 54, and a beam monitor device 60.

  The accelerator 40 is a device that generates a charged particle beam, and is, for example, a synchrotron, a cyclotron, or a linear accelerator. The charged particle beam generated by the accelerator 40 is guided to the sorting electromagnet apparatus 20 through the vacuum duct 70 whose interior is kept in a vacuum. When the charged particle beam irradiation device 100 includes the beam slit device 50, the quadrupole electromagnet device 52, and the steering electromagnet device 54, the accelerator 40, the beam slit device 50, the quadrupole electromagnet device 52, the steering electromagnet device 54, and the sorting electromagnet device. Each of the 20 is connected by a vacuum duct 70.

  The beam slit device 50 includes a slit that adjusts the beam shape and / or dose of a charged particle beam, and a controller that controls the slit width. As will be described later, the control unit may control the slit width based on information from the beam monitor device 60 to adjust the beam shape and / or dose.

  The quadrupole electromagnet apparatus 52 includes one or more quadrupole electromagnets for adjusting the beam shape of the charged particle beam, and a control unit that controls a current flowing through the quadrupole electromagnet and controls an adjustment amount of the beam shape. As will be described later, the control unit may control the amount of current flowing through the quadrupole electromagnet based on information from the beam monitor device 60 to adjust the beam shape. For example, the quadrupole electromagnet apparatus 52 includes at least two quadrupole electromagnets, a quadrupole electromagnet for adjusting the beam shape in the Y-axis direction and a quadrupole electromagnet for adjusting the beam shape in the Z-axis direction.

  The steering electromagnet device 54 includes one or more electromagnets for finely adjusting the beam position of the charged particle beam, and a control unit that controls a current flowing through the electromagnet and controls the beam position of the charged particle beam. The control unit may control the current passed through the electromagnet based on information from the beam monitor device 60 to adjust the beam position.

  Since the path of the charged particle beam from the distribution magnet 20 to the isocenter O varies depending on the irradiation angle θ, the optical element received by the charged particle beam also varies depending on the irradiation angle θ, and charging at the isocenter O is performed. The beam shape of the particle beam may change depending on the irradiation angle θ. In response to this, for example, the quadrupole electromagnet apparatus 52 provided on the upstream side of the focusing electromagnet 10 controls the current for exciting the quadrupole electromagnet for each irradiation angle θ, and the beam shape of the charged particle beam at the isocenter O. May be adjusted to be appropriate. The beam shape of the charged particle beam may be adjusted by the beam slitting device 50. Similarly in this case, the slit width of the beam slitting device 50 may be controlled for each irradiation angle θ.

  In order to maintain high irradiation accuracy, it is preferable to accurately control the irradiation angle θ of the charged particle beam irradiated to the isocenter O. However, the accuracy of the irradiation angle θ may decrease due to alignment errors of various devices of the charged particle beam irradiation apparatus 100 and magnetic field errors of various electromagnets. Therefore, a beam monitor device 60 for monitoring the position of the charged particle beam is provided on the exit side 17 of the focusing electromagnet 10, and information on the beam position and beam shape (beam width, etc.) of the charged particle beam is obtained from the beam monitor device 60 as a beam. Output to one or more of the irradiation angle control unit 33 of the power supply device 30 of the slitting device 50, the quadrupole electromagnet device 52, the steering electromagnet device 54, the distribution electromagnet device 20, and the converging electromagnet 10, and each performs feedback control. It is good to do so.

  For example, when information from the beam monitor device 60 is input, the beam slit device 50 controls the slit width to adjust the beam shape of the charged particle beam, and the quadrupole electromagnet device 52 controls the excitation current flowing through the quadrupole electromagnet to charge the beam. The beam shape of the particle beam is adjusted, the steering electromagnet device 54 controls the excitation current that flows through the electromagnet to adjust the beam position of the charged particle beam, and the sorting electromagnet device 20 controls the excitation current that flows through the electromagnet and emits it. The deflection angle φ of the charged particle beam is adjusted, or the irradiation angle control unit 33 adjusts the irradiation angle θ of the charged particle beam irradiated to the isocenter O.

  By feedback control using the beam monitor device 60, the irradiation accuracy with respect to the isocenter O can be further improved. The relationship between feedback information (beam position and beam shape) and adjustment amounts of the beam slit device 50, the quadrupole electromagnet device 52, the steering electromagnet device 54, the sorting electromagnet device 20, and the irradiation angle control unit 33. It is good to check beforehand and memorize | store in each apparatus beforehand.

  In the charged particle beam irradiation apparatus 100, a vacuum duct 72 for transporting the charged particle beam is provided between the sorting electromagnet apparatus 20 and the focusing electromagnet 10. The vacuum duct 72 is a fan-shaped (XY plane) vacuum duct that covers the range of the maximum deflection angle φ of the sorting electromagnet device 20. By making the shape of the vacuum duct 72 on the XY plane into a fan shape, the size can be reduced as compared with the rectangular shape, and the installation space can be reduced.

  The vacuum duct 72 may be a cylindrical vacuum duct connected to the exit of the sorting electromagnet device 20 as shown in FIG. With this structure, the vacuum duct can be further reduced in size and installation space can be reduced. In this case, the driving mechanism (not shown) is evacuated in the range from the positive maximum deflection angle (φmax) to the negative maximum deflection angle (−φmax) on the XY plane in conjunction with the deflection angle φ of the sorting electromagnet device 20. The duct 72 may be moved.

  FIG. 6 is a schematic diagram showing the use of the charged particle beam irradiation apparatus 100 for particle beam therapy for a patient. In the irradiation chamber for performing particle beam therapy in which the charged particle beam irradiation apparatus 100 is installed, the focusing electromagnet 10 is disposed with the longitudinal direction of the focusing electromagnet 10 being inclined with respect to the floor surface of the irradiation chamber. The ceiling height required for the installation can be kept low. In this case, since the traveling direction of the charged particle beam from the accelerator 40 and the isocenter O are not in a straight line, the line connecting the deflection starting point Q of the charged particle beam and the isocenter O in the sorting electromagnet apparatus 20 is the X axis. Then, as described in FIG. 2, the effective magnetic field regions 15a and 15b can be formed based on the relational expressions (1) to (5).

[Third Embodiment]
The third embodiment of the present invention relates to a charged particle beam irradiation apparatus 300 using a converging electromagnet 200 provided with a pair of coils 11a.

  As shown in FIGS. 7A and 7B, the converging electromagnet 200 according to this embodiment includes the coil pair 11a, the magnetic pole 12a, and the yoke 13 in the converging electromagnet 10 of the first embodiment. . Compared with the focusing electromagnet 10 of the first embodiment, the focusing electromagnet 200 can reduce the volume of the yoke 13 constituting the electromagnet by the amount of the coil pair 11b and the magnetic pole 12b, and can also reduce the weight of the focusing electromagnet 200.

  Although not shown, the charged particle beam irradiation apparatus 300 includes the sorting electromagnet apparatus 20, the power supply apparatus 30, and the accelerator 40 as in the second embodiment, and further passes through the focusing electromagnet 200 through the isocenter O. A driving device 220 that rotates around the X axis is included. The focusing electromagnet 200 and the sorting electromagnet 20 are connected through a vacuum duct 240. Although not shown, the charged particle beam irradiation apparatus 300 may further include at least one of a beam slit device 50, a quadrupole electromagnet device 52, a steering electromagnet device 54, and a beam monitor device 60. Good.

  As shown in FIG. 8, in the charged particle beam irradiation apparatus 300, the driving apparatus 220 rotates the focusing electromagnet 200 around the X axis, so that an arbitrary solid angle (rotation angle ω around the X axis and irradiation on the XY plane). The charged particle beam can be irradiated to the isocenter O from the range of the combination with the angle θ. In this way, the charged particle beam irradiation apparatus 300 enables particle beam treatment by three-dimensional multidirectional irradiation like a gamma knife mechanism without moving the patient.

[Fourth Embodiment]
In the fourth embodiment of the present invention, the charged particle beam irradiation apparatus 100 of the second embodiment (or the charged particle beam irradiation apparatus 300 of the third embodiment) is further provided with an image capturing apparatus 420 for viewing a target in the body. The present invention also relates to the charged particle beam irradiation apparatus 400.

  As shown in FIG. 9, an imaging apparatus 420 using X-ray or magnetic resonance technology is arranged near the patient, so that the target (malignant tumor) inside the patient can be detected before or during irradiation with the charged particle beam. The shape can be confirmed. If the shape of the target in the body can be confirmed using the image capturing device 420 before the irradiation of the charged particle beam, the charged particle beam to be irradiated can be accurately aligned with the position of the target. In addition, based on the image information captured by the image capturing device 420, it is possible to finely adjust the shape of the irradiation region (the shape of the charged particle beam) planned in advance according to the shape of the target that changes with time. Become. Further, the target may move or deform during the irradiation of the charged particle beam. Even in such a case, the image information of the target is acquired using the image capturing device 420 during the irradiation of the charged particle beam. Based on this information, the irradiation accuracy can be further improved by adjusting the shape of the charged particle beam manually or by the feedback control described in the second embodiment.

  The dimensions, materials, shapes, relative positions of components, and the like described in the above embodiments are changed according to the structure of the apparatus to which the present invention is applied or various conditions. It is not intended to be limited to the specific terms and embodiments used in the description, and other equivalent components can be used by those skilled in the art, and the above embodiments are within the spirit of the invention. Other variations and modifications are possible without departing from the scope. Also, features described in connection with one embodiment of the invention may be used with other embodiments, even if not explicitly described above.

DESCRIPTION OF SYMBOLS 10,200 Focusing electromagnet 11a, 11b Coil pair 12a, 12b Magnetic pole 13 Yoke 15a, 15b Effective magnetic field area 16 Incident side 17 of charged particle beam Ejection side 18 of charged particle beam 18 Bus bar 20 Distribution magnet device 30 Power supply device 31 Current switch 32 Power supply 33 Irradiation angle control unit 40 Accelerator 50 Beam slit device 52 Quadrupole electromagnet device 54 Steering electromagnet device 60 Beam monitor devices 70, 72 Vacuum ducts 100, 300, 400 Charged particle beam irradiation device 220 Drive device 420 Image photographing device

Claims (11)

A focusing electromagnet having a coil pair arranged so as to sandwich a path of a charged particle beam,
The coil pair is configured to generate an effective magnetic field region in which a magnetic field is directed in a direction (Z axis) orthogonal to a traveling direction (X axis) of a charged particle beam when current is input. The axis perpendicular to both the Z axis and the Y axis is the Y axis,
In the XY plane,
The charged particle beam deflected by the deflection angle φ with respect to the X axis at the deflection start point Q and incident on the effective magnetic field region is deflected by the effective magnetic field region, and is irradiated to the isocenter at an irradiation angle θ with respect to the X axis.
An arbitrary point P2 on the boundary of the effective magnetic field region on the emission side of the charged particle beam is located at an equal distance r ₁ from the isocenter,
The point P2 and the point P1 on the boundary of the entrance side of the charged particle beam of the effective magnetic field region is in a circular arc on a radius r ₂ and the central angle (theta + phi),
The distance R between the deflection starting point Q and the point P1 is represented by the relational expression (4), where L is the distance between the deflection starting point Q and the isocenter.
Satisfying the converging electromagnet. The convergence electromagnet includes two or more pairs of the coil pairs,
The two or more pairs of coils are arranged so as to sandwich the path of the charged particle beam and line up in the Y-axis direction,
A current switch is connected to the first coil pair and the second coil pair among the two or more coil pairs,
The current switch is configured to supply current to any one of the first coil pair and the second coil pair;
2. The converging electromagnet according to claim 1, wherein the first coil pair and the second coil pair are configured such that directions of magnetic fields in a generated effective magnetic field region are opposite to each other.   The focusing electromagnet according to claim 1, wherein the deflection starting point Q and the isocenter are on the X axis. An accelerator that generates a charged particle beam;
A focusing electromagnet device that deflects the charged particle beam from the accelerator at a deflection angle φ of 10 degrees or more at the deflection start point Q; and the focusing electromagnet according to any one of claims 1 to 3;
A power supply for supplying and exciting current to the converging electromagnet;
A charged particle beam irradiation apparatus. A vacuum duct connecting the distribution electromagnet device and the converging electromagnet;
The vacuum duct has a fan shape on an XY plane, and is configured to allow the charged particle beam deflected at the deflection angle φ of 10 degrees or more to pass through the vacuum duct. 4. The charged particle beam irradiation apparatus according to 4. A driving device for rotating the focusing electromagnet around the X axis at a rotation angle ω;
Further comprising
The charged particle beam irradiation apparatus according to claim 4 or 5, wherein the charged particle beam irradiation apparatus is configured to irradiate the isocenter with a charged particle beam from an arbitrary combination range of the rotation angle ω and the irradiation angle θ.   The said focusing electromagnet is comprised so that the longitudinal direction of the said focusing electromagnet can be inclined and arrange | positioned with respect to the floor surface of the irradiation chamber in which the said charged particle beam irradiation apparatus is installed. 2. The charged particle beam irradiation apparatus according to item 1.   The charged particle beam irradiation apparatus according to any one of claims 4 to 7, further comprising a quadrupole electromagnet provided on the upstream side of the sorting electromagnet apparatus and configured to adjust a beam shape of the charged particle beam.   The charged particle beam irradiation apparatus according to claim 8, wherein an excitation current of the quadrupole electromagnet is controlled for each irradiation angle θ in order to adjust a beam shape of the charged particle beam for each irradiation angle θ. A steering electromagnet device provided upstream of the distribution electromagnet device;
A beam monitor device provided on the exit side of the focusing electromagnet;
The feedback control of at least one exciting current among the sorting electromagnet device, the converging electromagnet, and the steering electromagnet is performed based on information on a beam position of the charged particle beam from the beam monitor device. The charged particle beam irradiation apparatus according to claim 1. It further has an image capturing device provided so as to sandwich the target in the isocenter,
The charged particle according to any one of claims 4 to 10, wherein the imaging device is configured to generate image information of the target before or during irradiation of the target with a charged particle beam. Beam irradiation device.