JP2019170705A - Neutron capture therapy apparatus and nuclear transmutation apparatus - Google Patents

Abstract

To detect whether or not an irradiation position on a target with a charged particle beam is normal and perform restoration in the case of detecting abnormality.SOLUTION: A neutron capture therapy apparatus 1A includes: an accelerator 10 for emitting a charged particle beam P; a target X for generating a neutron beam N using the charged particle beam P; a charged particle beam scan unit 34 for performing a scan with the charged particle beam P at a predetermined cycle along a predetermined orbit to change an irradiation position with the charged particle beam P; an annular current detection unit for detecting a current value of the charged particle beam P; an abnormality detection unit for detecting abnormality with respect to the irradiation position on the basis of a detection result of the current detection unit; and a beam adjustment unit 106 that on the basis of the detection result, performs adjustment of the charged particle beam P at a position closer to the accelerator 10 than the charged particle beam scan unit 34. The abnormality detection unit detects the abnormality with respect to the irradiation position for the target X with the charged particle beam P on the basis of a variation in the current value. The beam adjustment unit 106 adjusts a position or shape of the charged particle beam P on the basis of a result detected by the abnormality detection unit.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a neutron capture therapy apparatus and a transmutation apparatus.

  In a neutron capture therapy apparatus that irradiates an irradiated object with a neutron beam generated by irradiating a target with a charged particle beam, the irradiation position of the charged particle beam with respect to the target is required to be set correctly. For example, in Patent Document 1, when a current value is detected by a current detector installed along the inner wall of a beam transport path of a charged particle beam that generates a neutron beam, and the result is an abnormal state, the charged particle beam A configuration for stopping the irradiation of the line is shown.

JP 2015-217207 A

  However, the configuration described in Patent Document 1 cannot identify what is the cause when the current value is abnormal. Therefore, it is necessary to eliminate the abnormal state while checking each part of the apparatus. For this reason, it may take time to recover from the abnormal state.

  The present invention has been made in view of the above, and detects whether or not the irradiation position of a charged particle beam target is normal, and is able to be restored when it is detected that it is abnormal. An object is to provide a conversion device.

  In order to achieve the above object, a neutron capture therapy apparatus according to an aspect of the present invention includes an accelerator that emits a charged particle beam, a target that generates a neutron beam when irradiated with the charged particle beam, and the charged particle beam. And a charged particle beam scanning unit that changes the irradiation position of the charged particle beam to the target, and is disposed between the charged particle beam scanning unit and the target. , Detecting a current value of the charged particle beam, an annular current detection unit centering on an irradiation axis of the charged particle beam, and the detection result of the current detection unit to the target of the charged particle beam An anomaly detector that detects an anomaly related to the irradiation position, and a beam adjustment unit that adjusts the charged particle beam on the accelerator side of the charged particle beam scanning unit based on a detection result of the anomaly detector And The abnormality detection unit is configured to irradiate the target with the charged particle beam based on a change in a current value detected by the current detection unit when the charged particle beam is scanned by the charged particle beam scanning unit. The beam adjusting unit adjusts the position or shape of the charged particle beam based on the result detected by the abnormality detecting unit.

  In order to achieve the above object, a transmutation apparatus according to an aspect of the present invention includes an accelerator that emits a charged particle beam, a target that generates a neutron beam upon irradiation with the charged particle beam, and the charged particle beam. It is arranged between a charged particle beam scanning unit that scans with a predetermined orbit at a predetermined cycle and changes the irradiation position of the charged particle beam to the target, and the charged particle beam scanning unit and the target, Based on the detection result of the annular current detection unit centering on the irradiation axis of the charged particle beam and detecting the current value of the charged particle beam, the charged particle beam to the target An anomaly detector that detects an anomaly related to the irradiation position; and a beam adjustment unit that adjusts the charged particle beam on the accelerator side of the charged particle beam scanning unit based on a detection result of the anomaly detector. Have, before The abnormality detection unit is configured to detect an abnormality related to an irradiation position of the charged particle beam on the target based on a change in a current value detected by the current detection unit when the charged particle beam is scanned by the charged particle beam scanning unit. The beam adjusting unit adjusts the position or shape of the charged particle beam based on the result detected by the abnormality detecting unit.

  According to the neutron capture therapy device and the transmutation device described above, when a charged particle beam is scanned at the predetermined orbit in the orbit by the charged particle beam scanning unit, the current value detected by the current detection unit is changed. Based on the result, an abnormality relating to the irradiation position of the charged particle beam to the target is detected by the abnormality detecting unit, and the position or shape of the charged particle beam is adjusted by the beam adjusting unit based on the result. As described above, since the abnormality of the charged particle beam is detected in the abnormality detection unit and the charged particle beam is adjusted based on the result, whether the irradiation position of the charged particle beam with respect to the target is normal is detected. When it is detected, it can be restored.

  Here, the abnormality detection unit periodically changes the current value detected by the current detection unit when the charged particle beam is scanned at the predetermined cycle in the orbit. If there is a point at which the current value becomes the maximum value in a period ½ of the period, it can be determined that the charged particle beam has an abnormal shape.

  As described above, the current value detected by the current detection unit periodically changes, and there is a point where the maximum value of the current value is present in one period with a half of the period. In such a case, by determining that there is an abnormality in the shape of the charged particle beam, the abnormality detection unit appropriately detects an abnormality in the shape of the charged particle beam, and based on the result, the shape of the shape by the beam adjustment unit is detected. Adjustments can be made appropriately.

  In addition, the abnormality detection unit periodically changes the current value detected by the current detection unit when the charged particle beam is scanned at the predetermined cycle in the orbit. When there is a point that becomes the maximum value of the current value in a period ½ of the period and a point that becomes the minimum value of the current value, the position of the charged particle beam is abnormal. It can be set as the aspect judged.

  As described above, the current value detected by the current detection unit periodically changes, and becomes the maximum value of the current value in a period ½ of the period in one period, When there is a point where the current value is the minimum value, it is determined that there is an abnormality in the position of the charged particle beam, so that an abnormality in the position of the charged particle beam is appropriately detected by the abnormality detection unit. Then, based on the result, the position adjustment by the beam adjustment unit can be appropriately performed. Here, “abnormality of the position of the charged particle beam” refers to an abnormality of the irradiation position due to the movement of the irradiation axis of the charged particle beam.

  A neutron capture therapy apparatus according to an aspect of the present invention includes an accelerator that emits a charged particle beam, a target that generates a neutron beam upon irradiation with the charged particle beam, and the charged particle beam at a predetermined period. A charged particle beam scanning unit that scans in a predetermined orbit and changes the irradiation position of the charged particle beam to the target; and is disposed between the charged particle beam scanning unit and the target, and the charged particle beam One or more current detectors arranged to form a ring around the irradiation axis of the charged particle beam, and the charged particle beam based on the detection result of the current detector An abnormality detection unit for detecting an abnormality related to the irradiation position of the target, and adjustment of the charged particle beam on the accelerator side of the charged particle beam scanning unit based on a detection result in the abnormality detection unit Beam tone to perform And the abnormality detection unit is configured to detect the charged particle beam based on a current value detected by the one or more current detection units when the charged particle beam is scanned by the charged particle beam scanning unit. An abnormality related to the irradiation position on the target is detected, and the beam adjustment unit adjusts the position or shape of the charged particle beam based on the result detected by the abnormality detection unit.

  According to the neutron capture therapy apparatus, when charged particle beams are scanned at the predetermined cycle in the orbit by a charged particle beam scanning unit, charged particles are based on current values detected by a plurality of current detection units. An abnormality relating to the irradiation position of the line to the target is detected by the abnormality detection unit, and the position or shape of the charged particle beam is adjusted by the beam adjustment unit based on the result. As described above, since the abnormality of the charged particle beam is detected in the abnormality detection unit and the charged particle beam is adjusted based on the result, whether the irradiation position of the charged particle beam with respect to the target is normal is detected. When it is detected, it can be restored.

  ADVANTAGE OF THE INVENTION According to this invention, the neutron capture therapy apparatus and transmutation apparatus which can be returned when it detects that the irradiation position with respect to the target of a charged particle beam is normal, and are abnormal are provided.

It is a figure which shows the structure of the neutron capture therapy apparatus of 1st Embodiment. It is a schematic perspective view which shows the neutron beam production | generation part in the neutron capture therapy apparatus of FIG. It is a sectional side view which shows schematic structure of the electric current detection part shown in FIG. FIG. 4 is a transverse sectional view taken along line IV-IV shown in FIG. 3. It is a sectional side view which shows an example of the attachment structure of the electric current detection part shown in FIG. It is a figure explaining the relationship between the irradiation position of the charged particle beam P, and the change of the electric current value I. FIG. It is a figure explaining the relationship between the irradiation position of the charged particle beam P, and the change of the electric current value I. FIG. It is a figure explaining the relationship between the irradiation position of the charged particle beam P, and the change of the electric current value I. FIG. It is a figure explaining the relationship between the irradiation position of the charged particle beam P, and the change of the electric current value I. FIG. FIG. 5 is a flowchart for specifying the presence / absence of an abnormality in the irradiation position of a charged particle beam P with respect to a target X and its specific content. It is a figure explaining the method of analyzing the change of the electric current value I at the time of specifying abnormality of the irradiation position of the charged particle beam P with respect to the target X. FIG. It is a cross-sectional view corresponding to FIG. 4 of the electric current detection part with which the neutron capture therapy apparatus which concerns on 2nd Embodiment is provided.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
First, the outline | summary of the neutron capture therapy apparatus which concerns on 1st Embodiment is demonstrated using FIG.1 and FIG.2. The neutron capture therapy apparatus according to the present embodiment is, for example, a neutron capture therapy apparatus that performs cancer treatment using boron neutron capture therapy. As shown in FIGS. 1 and 2, the neutron capture therapy apparatus 1 </ b> A irradiates an irradiated body 40 such as a patient to which boron ( ¹⁰ B) is administered with a neutron beam N.

  The neutron capture therapy apparatus 1 </ b> A includes an accelerator 10. The accelerator 10 is an accelerator that accelerates charged particles such as protons to generate a proton beam (proton beam) as a charged particle beam P. In the present embodiment, a cyclotron is employed as the accelerator 10. The accelerator 10 has a capability of generating a charged particle beam P having a beam radius of 40 mm and 60 kW (= 30 MeV × 2 mA), for example. As the accelerator 10, other accelerators such as a synchrotron, a synchrocyclotron, or a linac may be used instead of the cyclotron.

  The charged particle beam P emitted from the accelerator 10 includes a horizontal steering 12, a four-direction slit 14, a horizontal vertical steering 16, a quadrupole electromagnet 18, 19, 20, a 90-degree deflection electromagnet 22, a quadrupole electromagnet 24, The light passes through the horizontal / vertical steering 26, the quadrupole electromagnet 28, the four-direction slit 30, the current monitor 32, and the charged particle beam scanning unit 34 sequentially, and is guided to the neutron beam generation unit 36. The charged particle beam P is irradiated to the target X in the neutron beam generation unit 36, whereby a neutron beam N is generated. The neutron beam N is applied to the irradiation object 40 on the treatment table 38.

  The horizontal steering 12 and the horizontal / vertical steering 16, 26 perform beam axis adjustment of the charged particle beam P using, for example, an electromagnet. Similarly, the quadrupole electromagnets 18, 19, 20, 24, and 28 suppress the divergence of the beam of the charged particle beam P using, for example, an electromagnet. The four-direction slits 14 and 30 perform beam shaping of the charged particle beam P by cutting off the end beam.

  The 90-degree deflecting electromagnet 22 deflects the traveling direction of the charged particle beam P by 90 degrees. The 90-degree deflection electromagnet 22 is provided with a switching unit 42, and the switching unit 42 can remove the charged particle beam P from the normal trajectory and guide it to the beam dump 44. The beam dump 44 confirms the output of the charged particle beam P before treatment or the like.

  The current monitor 32 measures the current value (that is, charge, irradiation dose rate) of the charged particle beam P irradiated to the target X in real time. As the current monitor 32, a non-destructive DCCT (DC Current Transformer) capable of measuring current without affecting the charged particle beam P is used. A controller 100 is connected to the current monitor 32. “Dose rate” means a dose per unit time (the same applies hereinafter).

  The controller 100 includes a control unit 102, a display unit 104, and a beam adjustment unit 106.

  The control unit 102 obtains the irradiation dose of the neutron beam N from the current value of the charged particle beam P measured by the current monitor 32, and controls the irradiation dose of the neutron beam N based on the irradiation dose. A ROM, a RAM, and the like are included.

  The display unit 104 displays the irradiation dose of the neutron beam N obtained by the control unit 102. For example, a display or a monitor is used.

  The beam adjustment unit 106 has a function as an abnormality detection unit that detects an abnormality related to the irradiation position of the charged particle beam P to the target based on a current detection result in a current detection unit 60 (see FIG. 2) described later. . The abnormality to be detected by the beam adjusting unit 106 is an abnormality in the beam shape of the charged particle beam P and an axial deviation of the beam axis.

  Further, the beam adjusting unit 106 performs adjustment related to the accelerator 10 and the charged particle beam P emitted from the accelerator 10 when an abnormality is detected (horizontal steering 12, four-direction slit 14, horizontal vertical steering 16). , Quadrupole electromagnets 18, 19, 20, 90-degree deflecting electromagnet 22, quadrupole electromagnet 24, horizontal / vertical steering 26, quadrupole electromagnet 28, and four-directional slit 30). As a function. The accelerator 10 to be controlled by the beam adjusting unit 106 and each unit for performing adjustment related to the charged particle beam P emitted from the accelerator 10 (horizontal steering 12, four-way slit 14, horizontal / vertical steering 16, quadrupole electromagnet 18, 19, 20, 90 degree deflection electromagnet 22, quadrupole electromagnet 24, horizontal / vertical steering 26, quadrupole electromagnet 28, 4-direction slit 30) are charged particles based on instructions from the beam adjustment unit 106. The irradiation position or shape of the line P is adjusted.

  The beam adjustment unit 106 is configured by, for example, a CPU, a ROM, a RAM, and the like. Note that information related to the abnormality detected by the beam adjustment unit 106 and information related to beam adjustment may be displayed on the display unit 104.

  The charged particle beam scanning unit 34 scans the charged particle beam P and performs irradiation control of the charged particle beam P with respect to the target X. The charged particle beam scanning unit 34 here controls, for example, the irradiation position of the charged particle beam P with respect to the target X, the beam diameter of the charged particle beam P, and the like. When the charged particle beam P is wobbled by the charged particle beam scanning unit 34 or the beam diameter of the charged particle beam P is increased, the irradiation region of the charged particle beam P on the target X is expanded. It is done. The wobbling operation refers to an operation of periodically moving the beam axis of the charged particle beam P having a constant beam diameter and expanding the irradiation area of the charged particle beam P to the target X by this periodic movement.

  In the present embodiment, the charged particle beam P is detected by the beam adjustment unit 106 by detecting the wobbling operation of the charged particle beam P by the charged particle beam scanning unit 34 by the current detection unit 60 in the subsequent stage. Based on the above, control related to beam adjustment is performed. This point will be described later.

  As shown in FIG. 2, the neutron beam generator 36 generates a neutron beam N by irradiating the target X with a charged particle beam P, and emits the neutron beam N through a collimator 46. The neutron beam generation unit 36 covers the target X disposed at the downstream end of the beam transport path 48 that transports the charged particle beam P, the moderator 50 that decelerates the neutron beam N generated by the target X, and these. And a shield 52 provided as described above.

  The target X generates a neutron beam N when irradiated with the charged particle beam P. The target X here is made of beryllium (Be), for example, and has a disk shape with a diameter of 160 mm. The moderator 50 decelerates the energy of the neutron beam N, and has, for example, a laminated structure made of a plurality of different materials. The shield 52 shields the generated neutron beam N and gamma rays generated by the generation of the neutron beam N so as not to be emitted to the outside, and is attached to the floor 54. The target X is not limited to a solid (plate shape) and may be a liquid.

  As shown in FIG. 2, the neutron capture therapy apparatus 1 </ b> A according to the present embodiment includes a current detection unit 60 that detects the current value of the charged particle beam P inside the beam transport path 48. The current detection unit 60 is disposed at a position between the charged particle beam scanning unit 34 and the neutron beam generation unit 36 inside the beam transport path 48. For example, an oscilloscope is connected to the current detection unit 60 via a wiring. The oscilloscope displays a waveform corresponding to the current value detected by the current detector 60. Based on the waveform of the oscilloscope, the current value detected by the current detector 60 is observed.

  The current detection unit 60 is connected to the beam adjustment unit 106 described above. The beam adjustment unit 106 controls the adjustment of the charged particle beam P by giving an instruction to each unit functioning as the beam adjustment unit based on the current value of the charged particle beam P detected by the current detection unit 60. . A specific control method by the beam adjusting unit 106 will be described later.

  Next, the configuration of the current detection unit 60 will be described in detail with reference to FIGS. 3 and 4. 3 is a side sectional view showing a schematic configuration of the current detection unit 60 shown in FIG. FIG. 4 is a cross-sectional view taken along the line IV-IV shown in FIG. As shown in FIGS. 3 and 4, the current detection unit 60 is formed in an annular shape along the inner wall 48 a.

  The current detection unit 60 has a substantially constant width, extends along the circumferential direction of the inner wall 48a, and has an outer peripheral surface and an inner peripheral surface that are bent with substantially the same curvature as the curvature of the inner wall 48a. The current detection unit 60 has a ring shape inside the inner wall 48a when viewed from the axial direction of the beam transport path 48 (see FIG. 4). In the present embodiment, since the inner wall 48a has a cylindrical shape, the current detection unit 60 is formed in a true circle. The current detection unit 60 has an opening 60 a as an opening through which a high-current charged particle beam passes in a central region in the radial direction of the beam transport path 48.

  The inner diameter of the current detection unit 60 is, for example, 14 to 17 cm, and the outer diameter of the current detection unit 60 is, for example, 16 to 19 cm. The current detector 60 is arranged in the beam transport path 48 at a position separated from the target X by, for example, about 35 cm.

  The current detection unit 60 detects the current of the charged particle beam P by contacting the charged particle beam P. The current detection unit 60 is made of a material that is conductive and hardly melts into heat. For example, the current detection unit 60 is made of a carbon material such as graphite or pure copper.

  As shown in FIG. 3, the distribution of the charged particle beam P passing through the inside of the beam transport path 48 includes a high current region R1 having a large current value (irradiation dose rate) and a low current value (irradiation dose rate). Current region R2. The low current region R2 surrounds the periphery of the high current region R1, and is a region closer to the inner wall 48a than the high current region R1 when the irradiation position of the charged particle beam P with respect to the target X is normal.

  The high current region R1 is a region having a current value of about 1 to 1.5 mA, for example. The low current region R2 is a region having a current value of, for example, about 2 to 3 μA. That is, the low current region R2 is a region having a current value of about 0.2% of the current value of the high current region R1, for example.

  The current detection unit 60 is installed so as to protrude from the inner wall 48 a side toward the inside of the beam transport path 48. That is, since the inner diameter of the current detection unit 60 is set to be smaller than at least the inner diameter of the inner wall 48a, the current detection unit 60 protrudes toward the inner circumference side of the beam transport path 48. As a result, the annular end surface of the current detection unit 60 is arranged in a state exposed in the beam transport path 48 as a detection surface of the charged particle beam P.

  The current detection unit 60 is formed so that the charged particle beam P in the low current region R2 is in contact with the charged particle beam P in a normal irradiation position with respect to the target X. The current detection unit 60 detects a minute current value of the charged particle beam P when the charged particle beam P in the low current region R2 comes into contact therewith.

  For example, when the beam diameter of the charged particle beam P is widened by the charged particle beam scanning unit 34 in a state where the irradiation position of the charged particle beam P with respect to the target X is normal, the current detection unit 60 includes the current detection unit 60. Is formed so as to be always in contact with the charged particle beam P in the low current region R2. Further, when the charged particle beam P is wobbling by the charged particle beam scanning unit 34 in a state where the irradiation position of the charged particle beam P with respect to the target X is normal, the current detection unit 60 It is formed so as to be in contact with the charged particle beam P in the low current region R2 at any position in the circumferential direction.

  The current detection unit 60 is formed so as not to contact the charged particle beam P in the high current region R1 when the irradiation position of the charged particle beam P with respect to the target X is normal. When the irradiation position of the charged particle beam P with respect to the target X is normal, the charged particle beam P in the high current region R1 passes through the opening 60a of the current detection unit 60.

  Next, an example of the mounting structure of the current detection unit 60 will be described with reference to FIG. FIG. 5 is a side sectional view showing an example of the mounting structure of the current detection unit 60 shown in FIG. As shown in FIG. 5, the current detection unit 60 is attached to the protrusion 48 b formed on the inner wall 48 a of the beam transport path 48 via the insulating member 5. The current detection unit 60 is attached to the projection 48b with the screw 3 in a state where the insulating member 5 is sandwiched between the current detection unit 60 and the projection 48b. That is, the current detection unit 60 is installed in a state insulated from the inner wall 48 a of the beam transport path 48. A plurality of fixing points between the current detection unit 60 and the protrusion 48b are provided at intervals from each other when viewed from the direction in which the beam transport path 48 extends. The inner wall 48a and the outer peripheral surface of the current detection unit 60 are separated from each other in order to insulate the inner wall 48a and the current detection unit 60 from each other.

  Next, an abnormality detection by the beam adjustment unit 106 based on the current value detected by the current detection unit 60 and a beam adjustment method based on the detection result will be described in detail.

  As shown in FIG. 2, the beam adjustment unit 106 determines the beam shape and the axis deviation based on the control information related to the wobbling operation in the charged particle beam scanning unit 34 and the information detected in the current detection unit 60. The evaluation concerning is performed. Based on the result, control related to adjustment related to the shape and axis of the beam is performed.

  The control related to the wobbling operation of the charged particle beam P by the charged particle beam scanning unit 34 means that the target X is irradiated with the charged particle beam P by periodically moving the beam axis of the charged particle beam P having a constant beam diameter. This control is to change the position periodically. More specifically, the beam is generated using an electromagnet or the like so that the beam axis of the charged particle beam P circulates in a circular (true circular) path having a predetermined diameter centered on the beam axis of the original charged particle beam P. The axis is controlled. Therefore, the irradiation position of the charged particle beam P is periodically changed as the beam axis goes around a circular path with a predetermined period T.

  The beam adjusting unit 106 acquires information related to the change period T of the irradiation position of the charged particle beam P in the charged particle beam scanning unit 34 from the charged particle beam scanning unit 34. That is, the beam adjustment unit 106 acquires information related to the control of the irradiation position of the charged particle beam P at the time t from the charged particle beam scanning unit 34. Further, the beam adjustment unit 106 acquires information related to the current value detected at time t from the current detection unit 60. The beam adjusting unit 106 evaluates whether there is an abnormality in the shape of the charged particle beam P by combining these.

  This will be specifically described with reference to FIGS.

  The beam transport around the beam axis of the charged particle beam P by the charged particle beam scanning unit 34 is an irradiation axis that is the original beam axis (the beam axis when the beam axis is not controlled by the charged particle beam scanning unit 34). It is a circumferential path around the center axis of the road. The irradiation position of the charged particle beam P around the beam axis of the charged particle beam P also corresponds to the above-described circulation path. Further, the beam shape of the charged particle beam P having a normal irradiation position with respect to the target X is a perfect circle. Therefore, the charged particle beam scanning unit 34 performs a wobbling operation on the charged particle beam P having a normal beam shape and beam axis (that is, the beam shape is a perfect circle and the beam axis is not misaligned). In this case, the outer peripheral shape of the charged particle beam P should be a perfect circle centered on the original beam axis at the center of the beam transport path.

  FIG. 6A shows an irradiation range of the charged particle beam P when the charged particle beam P in which the irradiation position with respect to the target X is in a normal state is operated. FIG. 6B shows a change in the current value I detected by the current detector 60 when a normal charged particle beam P is subjected to a wobbling operation. In the example shown in FIGS. 6A and 6B, a state in which the charged particle beam P is rotated clockwise in the period T along the above-described circulation path is shown. In FIG. 6A, the circular path C1 of the beam axis of the charged particle beam P is schematically shown (the diameter of the circular path C1 may be larger than that shown in FIG. 6). At time t = 0, the charged particle beam scanning unit is configured such that the beam axis of the charged particle beam P is positioned above the center C in the circulation path C1 centering on the center C of the beam transport path 48. 34. At time t = T / 4, the charged particle beam P is such that the beam axis of the charged particle beam P is positioned on the right side with respect to the center C in the circulation path C1 centered on the center C of the beam transport path 48. It is controlled by the scanning unit 34. At time t = T / 2, the charged particle beam P is charged so that the beam axis of the charged particle beam P is positioned below the center C in the circulation path C1 centered on the center C of the beam transport path 48. It is controlled by the particle beam scanning unit 34. At time t = 3T / 4, the charged particle beam P is such that the beam axis of the charged particle beam P is positioned on the left side with respect to the center C in the circulation path C1 centered on the center C of the beam transport path 48. It is controlled by the scanning unit 34.

  The outer shape S of the charged particle beam P when the irradiation position of the charged particle beam P is changed by making the beam axis of the charged particle beam P one round along the circulation path is centered on the center C of the beam transport path 48. It becomes a round shape. In this case, the position where the irradiation position of the charged particle beam P that circulates along the circulation path and the current detection unit 60 overlap is constant regardless of the irradiation position of the charged particle beam P. Accordingly, the current value detected by the current detector 60 does not change regardless of the position of the beam axis of the charged particle beam P in the circuit path. Therefore, as shown in FIG. 6B, the current value I detected by the current detector 60 is constant while the time t changes from 0 to T.

  Next, consider a case where the beam shape changes as shown in FIG. FIG. 7A shows an irradiation range of the charged particle beam P when the wobbling operation is performed on the charged particle beam P whose beam shape is a flat circular shape. FIG. 7B shows a change in the current value I detected by the current detector 60 when the charged particle beam P is subjected to a wobbling operation.

  As shown in FIG. 7A, it is assumed that the beam shape is deformed to be horizontally long compared to a perfect circle. The outer shape S of the charged particle beam P when the irradiation position of the charged particle beam P is changed by making the beam axis of the deformed charged particle beam P one round along the circulation path is similar to the beam shape. It becomes a horizontally long flat circular shape centering on the center C of the road 48. In this case, the size of the region where the irradiation position of the charged particle beam P that circulates along the circulation path and the current detection unit 60 overlap changes according to the irradiation position of the charged particle beam P.

  Specifically, as shown in FIG. 7A, in the vicinity of t = T / 4 and t = 3T / 4, the area where the current detection unit 60 and the charged particle beam P overlap with each other increases. As shown in (B), the current value I detected by the current detector 60 increases, and becomes maximum at t = T / 4 and t = 3T / 4. On the other hand, in the vicinity of t = T / 2 and t = T, the area where the current detection unit 60 and the charged particle beam P overlap with each other is small, so the current value I detected by the current detection unit 60 is small, and t = T Minimum at / 2 and t = T.

  Thus, when the beam shape changes from a perfect circle to a flat circle shape, two current value I peaks (points) occur with the interval being T / 2. That is, a point (peak: local maximum point) having a maximum value repeatedly appears in a half period of the orbital period in the orbit. The position where the peak occurs varies depending on in which direction the long side of the beam is generated. When the beam axis of the charged particle beam P is not shifted from the original position, the maximum values of the current values I at the two peaks are substantially the same as shown in FIG.

  Next, consider a case where the beam axis of the charged particle beam P is deviated (moved) from the original position of the beam axis (center C of the beam transport path 48). FIG. 8A shows an irradiation range of the charged particle beam P when the charged particle beam P in which the beam axis is shifted to the left from the center of the beam transport path 48 is operated. FIG. 8B shows a change in the current value I detected by the current detection unit 60 when the charged particle beam P is subjected to a wobbling operation.

  As described above, it is assumed that the beam shape of the charged particle beam P is not deformed and only the beam axis has moved to the left from the center C of the beam transport path 48. The outer shape S of the charged particle beam P when the irradiation position of the charged particle beam P is changed by making the beam axis of the charged particle beam P whose beam axis is deviated from the original position one round along the circulation path is as follows: As shown in FIG. 8 (A), it becomes a perfect circle shape centered on a shifted position rather than the center C of the beam transport path 48. In this case, the size of the region where the irradiation position of the charged particle beam P that circulates along the circulation path and the current detection unit 60 overlap changes according to the irradiation position of the charged particle beam P.

  Specifically, as shown in FIG. 8A, since the area where the current detection unit 60 and the charged particle beam P overlap is increased between t = T / 2 and T, the pattern shown in FIG. As shown, the current value I detected by the current detector 60 increases and becomes maximum at t = 3T / 4. On the other hand, since the area where the current detection unit 60 and the charged particle beam P overlap is small between 0 and T / 2, the current value I detected by the current detection unit 60 is small, and is minimum at t = T / 4. It becomes.

  Thus, when the beam axis is deviated from the original position (center C of the beam transport path 48), the point of the maximum value of one large current value I (peak: local maximum point) according to the deviated direction. And a minimum point (downward peak: local minimum point) is generated with an interval T / 2 from the peak. In other words, the maximum value point and the minimum value point appear alternately in a half period of the orbital period in the orbit. The position where the peak occurs changes according to the axial deviation direction of the beam axis. Further, the peak size changes according to the amount of axial deviation.

  Next, consider a case where the beam shape of the charged particle beam P is deformed and the beam axis is deviated (moved) from the original position of the beam axis (center C of the beam transport path 48). FIG. 9A shows a charged particle beam P when a wobbling operation is performed on the charged particle beam P in a state where the beam shape is a horizontally long flat circle shape and the beam axis is shifted to the right from the center of the beam transport path 48. The irradiation range is shown. FIG. 9B shows a change in the current value I detected by the current detection unit 60 when the charged particle beam P is subjected to a wobbling operation.

  As described above, it is assumed that the beam shape of the charged particle beam P is not deformed and only the beam axis has moved to the left from the center C of the beam transport path 48. Charged particle beam when the beam shape is deformed and the irradiation position of the charged particle beam P is changed by rotating the beam axis of the charged particle beam P whose beam axis is deviated from the original position along the circuit path. As shown in FIG. 9A, the outer shape S of P has a flat circular shape centered on a shifted position, not the center C of the beam transport path 48. In this case, the size of the region where the irradiation position of the charged particle beam P that circulates along the circulation path and the current detection unit 60 overlap changes according to the irradiation position of the charged particle beam P.

  Specifically, as shown in FIG. 9A, since the area where the current detection unit 60 and the charged particle beam P overlap is large between t = 0 and T / 2, FIG. As shown, the current value I detected by the current detector 60 increases and becomes maximum at t = T / 2. On the other hand, since the area where the current detection unit 60 and the charged particle beam P overlap is small between T / 2 and T, the current value I detected by the current detection unit 60 is small. However, since the shape of the beam is flat, a small peak is formed even at t = 3T / 4.

  As described above, when the beam shape is flat and the beam axis is deviated from the original position (center C of the beam transport path 48), the change in the current value I described in FIGS. 7 and 8 is combined. It becomes a state.

  The beam adjusting unit 106 detects a change in the beam shape and a deviation of the beam axis from the change in the current value I at time t as described above. Further, as described above, how the beam shape is changed and how the beam axis is deviated can also be obtained from the change in the current value I. Therefore, the beam adjusting unit 106 identifies an abnormality of the charged particle beam P and performs adjustment for correcting the abnormality.

  With reference to FIG. 10 and FIG. 11, a specific procedure for specifying whether there is an abnormality in the irradiation position of the charged particle beam P with respect to the target X in the beam adjusting unit 106 and adjusting the charged particle beam P will be described. FIG. 10 is a flow chart for specifying the presence / absence of abnormality of the irradiation position of the charged particle beam P with respect to the target X and the specific content thereof (detecting the abnormality). FIG. 11 is a diagram for explaining a method for analyzing a change in the current value I when an abnormality in the irradiation position of the charged particle beam P with respect to the target X is specified. The beam adjustment unit 106 holds information related to the wobbling operation in the charged particle beam scanning unit 34 (information specifying in which direction the beam position is moved at time t), and the current detection unit 60 supplies the current at time t. It is assumed that detection information of value I is acquired. In the present embodiment, as shown in FIGS. 6 to 9, assuming that the center of the beam axis of the charged particle beam P is at the top of the circulation path C1 at t = 0, the circulation path C1 is rotated clockwise with the period T. A case where the charged particle beam scanning unit 34 controls the wobbling operation so as to make one round will be described. Note that the flowchart shown in FIG. 10 is an example, and is not limited to the procedure shown in FIG.

  First, the beam adjustment unit 106 acquires information related to a change in the current value I related to one cycle from t = 0 (or after N cycles). Then, it is confirmed whether or not there is a change in the current value I during one cycle and there is a maximum peak (maximum point) (S01). When there is no peak (S01-NO), since there is no abnormality in the charged particle beam P, the control related to the charged particle beam P is not performed. On the other hand, when there is a peak (S01-YES), since there is some abnormality in the charged particle beam P, data relating to the current value I is analyzed.

First, the current value I for one cycle T is analyzed to obtain peak values in two regions (S02). Specifically, as shown in FIG. 11A, data relating to the current value I for one period T (time t = 0 to T) is divided into two time zones A and B. The time zone A is t = 0 to 3T / 8, 7T / 8 to T (corresponding to t = −T / 8 to 3T / 8), and the time zone B is t = 3T / 8 to 7T / 8. is there. Both time zones A and B are data having a time width of T / 2. After the data related to the current value I is divided into two time zones A and B, the peak (maximum point) of the current value I in each time zone is specified, and the current value I at each peak is set to I _A , I _B.

Here, the beam adjustment unit 106 determines whether I _A = I _B (S03). When I _A = I _B (S03-YES), there is a maximum point (peak) in the change in the current value I, but the peak values in the two time zones A and B are the same. As in the example shown in FIG. 7, it is determined that an abnormality occurs in the peak shape.

Therefore, further data analysis is performed to determine how the peak shape abnormality is specifically occurring (S04). Specifically, as shown in FIG. 11 (B), the data related to the current value I in the two time zones A and B are divided into two to be time zones 1, 2, 3, and 4, respectively. Time zone 1 is t = 0 to T / 8, 7T / 8 to T (corresponding to t = −T / 8 to T / 8), and time zone 2 is t = T / 8 to 3T / 8. is there. The time zone 3 is t = 3T / 8 to 5T / 8, and the time zone 4 is t = 5T / 8 to 7T / 8. All of the time zones 1 to 4 are data having a time width of T / 4. After the data related to the current value I is divided into four time zones 1 to 4, the peak (maximum point) of the current value I in each time zone is specified, and the current value I at each peak is set to I ₁ , I ₂ , I ₃ , and I ₄ .

Here, the beam adjustment unit 106 determines whether I ₁ > I ₂ (S05). When I ₁ > I ₂ (S05-YES), it is determined that the beam shape is a flat circular shape deformed vertically and the deformation element is adjusted according to the peak value I ₁ (S06). . On the other hand, if I ₁ > I ₂ is not satisfied (S05-NO), it is determined that the beam shape is a flat circular shape deformed horizontally, and the deformation element is adjusted according to the peak value I ₂ ( S07).

  In the case of a flat circular shape, the beam adjustment unit 106 performs control related to the adjustment of the beam shape with respect to the quadrupole electromagnets 18, 19, 20, 24, 28, and the like, for example. A case where the control related to the adjustment of the beam shape is performed on the accelerator 10 is also conceivable. The beam adjusting unit 106 stores in advance information on the electromagnet or the accelerator 10 that is assumed to affect the deformation of the beam shape, and what kind of abnormality has occurred and the magnitude of the abnormality (for example, the deformation amount). ) And the like, the beam shape is corrected by controlling the respective units preceding the charged particle beam scanning unit 34.

Then, the beam adjuster _106, determines whether the _I A = I _B (S03) the _result, if not the _{I A = I B (S03-} NO), 2 single time zone A, the current in the B Since the peak value (maximum value) of the value I is not the same, it is determined that an abnormality occurs in the beam axis.

Therefore, further data analysis is performed in order to determine how the beam axis abnormality is specifically occurring (S08). Specifically, as shown in FIG. 11 (B), the data related to the current value I in the two time zones A and B are divided into two to be time zones 1, 2, 3, and 4, respectively. Time zone 1 is t = 0 to T / 8, 7T / 8 to T (corresponding to t = −T / 8 to 1T / 8), and time zone 2 is t = T / 8 to 3T / 8. is there. The time zone 3 is t = 3T / 8 to 5T / 8, and the time zone 4 is t = 5T / 8 to 7T / 8. All of the time zones 1 to 4 are data having a time width of T / 4. After the data related to the current value I is divided into four time zones 1 to 4, the peak (maximum point) of the current value I in each time zone is specified, and the current value I at each peak is set to I ₁ , I ₂ , I ₃ , and I ₄ .

Here, the beam adjustment unit 106 determines whether I ₁ > I ₂ (S09). If I ₁ > I ₂ is not satisfied (S05-NO), it is determined that the beam axis is biased in the left-right direction (shifted to either the left or right) (S10). Then, in order to determine whether it is shifted to the left or right, it is determined whether I ₂ > I ₄ (S11). When I ₂ > I ₄ is not satisfied (S11-NO), it is determined that the beam axis is biased to the I ₄ side (t = 3T / 4 side), that is, the left side, and the deformation element is determined according to the peak value I _4. (S12). On the other hand, when I ₂ > I ₄ (S11-YES), it is determined that the beam axis is biased to the I ₂ side (t = T / 4 side), that is, the right side, and the peak value I ₂ is determined. The deformation element is adjusted (S13).

Next, the beam adjustment unit 106 determines whether or not I ₁ > I ₂ (S09). If I ₁ > I ₂ (S05-YES), the beam axis is moved vertically from the current value I. It is determined that there is a bias (shifted up or down) (S14). Then, in order to determine whether the deviation above or _{below, and} determines whether the _{I 1> I 3 (S15)} . When I ₁ > I ₃ is not satisfied (S15-NO), it is determined that the beam axis is biased to the I ₃ side (t = T / 2 side), that is, the lower side based on the current value I, and the peak value adjusting the deformation element according to I ₃ (S16). On the other hand, if I ₁ > I ₃ (S15—YES), it is determined that the beam axis is biased to the I ₁ side (t = 0 side), that is, the upper side based on the current value I, and the peak value I _The deformation element is adjusted according to ₁ (S17).

  If there is a deviation in the position of the beam axis, the beam adjustment unit 106 performs control related to the adjustment of the beam axis, for example, with respect to the horizontal steering 12, the horizontal / vertical steering 16, 26, and the like. Further, a case where the control related to the adjustment of the beam axis is performed on the accelerator 10 can be considered. The beam adjustment unit 106 stores in advance information such as the steering or the accelerator 10 that is assumed to affect the movement of the beam axis, and what kind of abnormality has occurred and the magnitude of the abnormality (for example, an axis shift). The position of the beam axis is corrected by controlling each part of the stage prior to the charged particle beam scanning unit 34 according to the amount).

  A series of processes (S01 to S17) are repeatedly performed. Therefore, when there is an abnormality in both the beam shape and the beam axis, for example, correction of the above-described vertical or horizontal beam axis misalignment (S12, S13, S16) by analysis and correction related to the first beam. , S17), the axis deviation is corrected. After the correction, the abnormality related to the axis deviation is resolved, but it is considered that the abnormality related to the beam shape still remains. Therefore, only an abnormality in the beam shape is detected (S03-YES), and adjustment related to the beam shape can be performed. In this way, the beam shape and the beam axis can be adjusted by repeating a series of processes (S01 to S17).

  As described above, according to the neutron capture therapy apparatus 1A according to the present embodiment, when the charged particle beam P is scanned at a predetermined period T in the orbit by the charged particle beam scanning unit 34, the current detection unit 60 detects the charged particle beam P. The beam adjustment unit 106 as an abnormality detection unit detects an abnormality related to the irradiation position of the charged particle beam P on the target X based on the change in the current value I, and the beam adjustment unit 106 detects the charged particle based on the result. The position or shape of the line is adjusted. As described above, since the abnormality of the charged particle beam P is detected and the charged particle beam is adjusted based on the result, whether or not the irradiation position of the charged particle beam P with respect to the target X is normal is detected. When this is detected, it can be restored.

  Further, in the beam adjustment unit 106 serving as the abnormality detection unit, the current value I detected by the current detection unit 60 changes periodically, and the current has a period ½ of the period in one cycle. When there is a point (maximum point) having the maximum value I, it is determined that there is an abnormality in the shape of the charged particle beam P. By adopting such a configuration, abnormality in the shape of the charged particle beam is appropriately detected by the beam adjustment unit 106 (abnormality detection unit), and the shape adjustment by the beam adjustment unit 106 is appropriately performed based on the result. Can do.

  Further, in the beam adjustment unit 106 serving as the abnormality detection unit, the current value I detected by the current detection unit 60 changes periodically, and the current has a period ½ of the period in one cycle. If there is a point (maximum point) that is the maximum value I and a point (minimum point) that is the minimum value of the current value I, it is determined that the position of the charged particle beam P is abnormal. By adopting such a configuration, an abnormality in the position of the charged particle beam is appropriately detected by the beam adjustment unit 106 (abnormality detection unit), and the position adjustment by the beam adjustment unit 106 is appropriately performed based on the result. Can do.

(Second Embodiment)
Next, the configuration of the neutron capture therapy apparatus according to the second embodiment will be described. In the description of the present embodiment, differences from the first embodiment will be mainly described.

  Similar to the first embodiment, the neutron capture therapy apparatus 1B according to the present embodiment includes an accelerator 10, a target X, and a beam transport path 48 (see FIG. 1). This neutron capture therapy apparatus 1B is different from the neutron capture therapy apparatus 1A according to the first embodiment in that it includes a plurality of current detection units. Hereinafter, the configuration of the current detection unit according to the present embodiment will be described with reference to FIG. FIG. 12 is a cross-sectional view corresponding to FIG. 4 of the current detection unit provided in the neutron capture therapy apparatus 1B according to the second embodiment.

  As shown in FIG. 12, the neutron capture therapy apparatus 1B according to the second embodiment includes, for example, four current detection units 61 along the inner wall 48a. The electric current detection part 61 is arrange | positioned so that it may become cyclic | annular. The adjacent current detectors 61 are insulated from each other by the insulating member 5. Each current detection unit 61 detects the current value of the charged particle beam P in the low current region R2 that is in contact therewith.

  In the neutron capture therapy apparatus 1B according to the second embodiment, when the irradiation position of the charged particle beam P is periodically changed in the charged particle beam scanning unit 34, similarly to the neutron capture therapy apparatus 1A, in the current detection unit 61 Information related to the detected current value I is sent to a beam adjustment unit 106 as an abnormality detection unit, and the beam adjustment unit 106 evaluates whether there is an abnormality.

  However, in the neutron capture therapy apparatus 1A, the beam adjustment unit 106 has evaluated the change in the current value I from one current detection unit 60, whereas in the neutron capture therapy apparatus 1B, the beam adjustment unit 106 has a plurality of changes. The presence / absence of an abnormality related to the position and shape of the charged particle beam P is evaluated by combining information on the current value I from the current detector 61. In this case, in the neutron capture therapy apparatus 1B, even if there is no information from the charged particle beam scanning unit 34, it is possible to evaluate whether there is an abnormality.

  When the plurality of current detection units 61 are arranged in a ring shape as in the neutron capture therapy apparatus 1B, when the charged particle beam P is scanned by the charged particle beam scanning unit 34, among the plurality of current detection units 61 Only a part of the current detectors 61 are irradiated with the charged particle beam P. In addition, the plurality of current detection units 61 are arranged at different positions. Therefore, the beam adjustment unit 106 does not know the scanning period in the charged particle beam scanning unit 34, but how the charged particle beam P is based on the information of the current value I from the plurality of current detection units 61. It is possible to grasp whether the scanning is performed. Therefore, when there is an abnormality in the irradiation position of the charged particle beam P with respect to the target X, also in the neutron capture therapy apparatus 1B, the beam adjustment unit 106 similarly applies the charged particle beam P to the target X as in the neutron capture therapy apparatus 1A. An abnormality related to the irradiation position is detected by the beam adjustment unit 106 as an abnormality detection unit, and the position or shape of the charged particle beam is adjusted by the beam adjustment unit 106 based on the result. As described above, since the abnormality of the charged particle beam P is detected and the charged particle beam is adjusted based on the result, whether or not the irradiation position of the charged particle beam P with respect to the target X is normal is detected. When this is detected, it can be restored.

  In addition, the specific procedure of the control regarding abnormality detection and beam adjustment in the beam adjustment unit 106 of the neutron capture therapy apparatus 1B can be the same as that of the neutron capture therapy apparatus 1A.

  Moreover, when arrange | positioning the several electric current detection part 61, the abnormality of the position or shape of the charged particle beam P can be detected appropriately by arrange | positioning the four electric current detection parts 61 cyclically | annularly, for example. However, the number of the current detection units 61 may be more than four. In that case, the abnormality of the position or shape of the charged particle beam P can be analyzed in more detail. Even when the number of the current detection units 61 is small, it is possible to detect an abnormality in the position or shape of the charged particle beam P by devising the arrangement and shape of the current detection unit 61. Therefore, the number of the current detection units 61 to be arranged is not particularly limited as long as it is 1 or more.

  The preferred embodiments of the present embodiment have been described above. However, the present invention is not limited to the above-described embodiments. The present invention is not limited to the scope described in the claims and can be modified or applied to others. It may be what you did.

  In the above embodiment, a plurality of current detectors 60 and 61 provided in the beam transport path 48 may be arranged along the beam transport path 48 in order to improve the reliability of information.

  In the above embodiment, the beam adjustment unit 106 performs control when the irradiation position of the charged particle beam P with respect to the target X is in an abnormal state. However, the present invention is not limited to this. For example, the neutron capture therapy apparatus 1A, 1B detects an abnormality of the charged particle beam P and outputs information necessary for adjusting the beam (for example, information indicating how much abnormality has occurred). The operator of the neutron capture therapy devices 1A and 1B may perform a work such as changing the setting of the electromagnet related to the adjustment of the beam of the charged particle beam P.

  In the said embodiment, although neutron capture therapy apparatus 1A, 1B was described, it replaced with this and the transmutation apparatus using a nuclear spallation reaction may be sufficient. The transmutation device includes, for example, a radioisotope production device. In this case, as in the neutron capture therapy apparatuses 1A and 1B, the transmutation apparatus generates various nuclei or neutrons by the fragmentation reaction upon receiving the charged particle beam P and the accelerator 10 that emits the charged particle beam P. A target X, a beam transport path 48 that transports the charged particle beam P emitted from the accelerator 10, and a current detector 60 that detects a current value of the charged particle beam P. The current detector 60 includes a beam Inside the transport path 48, it is installed along the inner wall 48a while being insulated from the inner wall 48a. In such a transmutation device, as in the neutron capture therapy devices 1A and 1B, an abnormality of the charged particle beam P is detected and the charged particle beam is adjusted based on the result. It is possible to detect whether or not the irradiation position with respect to the target X is normal, and to return when it is detected that the target X is abnormal.

  DESCRIPTION OF SYMBOLS 1A, 1B ... Neutron capture therapy apparatus, 10 ... Accelerator, 48 ... Beam transport path, 60, 61 ... Current detection part, 106 ... Beam adjustment part, P ... Charged particle beam, N ... Neutron beam, X ... Target.

Claims (5)

An accelerator that emits a charged particle beam;
A target for generating a neutron beam upon irradiation with the charged particle beam;
A charged particle beam scanning unit that scans the charged particle beam in a predetermined orbit with a predetermined period and changes an irradiation position of the charged particle beam to the target; and
An annular current detection unit centered on an irradiation axis of the charged particle beam, which is disposed between the charged particle beam scanning unit and the target and detects a current value of the charged particle beam;
Based on the detection result in the current detection unit, an abnormality detection unit that detects an abnormality related to the irradiation position of the charged particle beam to the target; and
A beam adjusting unit that adjusts the charged particle beam on the accelerator side of the charged particle beam scanning unit based on the detection result in the abnormality detecting unit;
Have
The abnormality detection unit relates to an irradiation position of the charged particle beam to the target based on a change in a current value detected by the current detection unit when the charged particle beam is scanned by the charged particle beam scanning unit. Detect anomalies,
The beam adjustment unit is a neutron capture therapy apparatus that adjusts the position or shape of the charged particle beam based on a result detected by the abnormality detection unit.   The abnormality detection unit periodically changes the current value detected by the current detection unit when the charged particle beam is scanned at the predetermined cycle in the orbit, and the period is changed during one cycle. 2. The neutron capture therapy apparatus according to claim 1, wherein when there is a point that has a maximum value of the current value in a period of ½, the charged particle beam is determined to be abnormal.   The abnormality detection unit periodically changes the current value detected by the current detection unit when the charged particle beam is scanned at the predetermined cycle in the orbit, and the period is changed during one cycle. If there is a point where the current value becomes the maximum value and a point where the current value becomes the minimum value at a period ½ of the current value, it is determined that there is an abnormality in the position of the charged particle beam. The neutron capture therapy apparatus according to claim 1. An accelerator that emits a charged particle beam;
A target for generating a neutron beam upon irradiation with the charged particle beam;
A charged particle beam scanning unit that scans the charged particle beam in a predetermined orbit with a predetermined period and changes an irradiation position of the charged particle beam to the target; and
One or more currents arranged between the charged particle beam scanning unit and the target and arranged in an annular shape around the irradiation axis of the charged particle beam for detecting a current value of the charged particle beam A detection unit;
Based on the detection result in the current detection unit, an abnormality detection unit that detects an abnormality related to the irradiation position of the charged particle beam to the target; and
A beam adjusting unit that adjusts the charged particle beam on the accelerator side of the charged particle beam scanning unit based on the detection result in the abnormality detecting unit;
Have
The abnormality detection unit relates to an irradiation position of the charged particle beam to the target based on a current value detected by the one or more current detection units when the charged particle beam scanning unit scans the charged particle beam. Detect anomalies,
The beam adjustment unit is a neutron capture therapy apparatus that adjusts the position or shape of the charged particle beam based on a result detected by the abnormality detection unit. An accelerator that emits a charged particle beam;
A target for generating a neutron beam upon irradiation with the charged particle beam;
A charged particle beam scanning unit that scans the charged particle beam in a predetermined orbit with a predetermined period and changes an irradiation position of the charged particle beam to the target; and
An annular current detection unit centered on an irradiation axis of the charged particle beam, which is disposed between the charged particle beam scanning unit and the target and detects a current value of the charged particle beam;
Based on the detection result in the current detection unit, an abnormality detection unit that detects an abnormality related to the irradiation position of the charged particle beam to the target; and
A beam adjusting unit that adjusts the charged particle beam on the accelerator side of the charged particle beam scanning unit based on the detection result in the abnormality detecting unit;
Have
The abnormality detection unit relates to an irradiation position of the charged particle beam to the target based on a change in a current value detected by the current detection unit when the charged particle beam is scanned by the charged particle beam scanning unit. Detect anomalies,
The beam adjusting unit is a transmutation device that adjusts a position or a shape of the charged particle beam based on a result detected by the abnormality detection unit.