JP2018201774A - Neutron capture therapy device and target for neutron capture therapy - Google Patents

Abstract

To provide a neutron capture therapy device capable of suppressing deterioration of a detection part and grasping dose distribution of a charged particle ray, and a target for neutron capture therapy.SOLUTION: A neutron capture therapy device comprises a detection part 100 for detecting a current value of a charged particle ray by contacting the charged particle ray. The detection part 100 directly contacts the charged particle ray for detecting the current value, so that, using the detection result of the detection part 100, it is possible to grasp a dose distribution of the charged particle ray. The detection part 100 contacts the target 10. Therefore, even when a large current charged particle ray is radiated to the detection part 100 and heat is generated on the detection part 100, heat on the detection part 100 is diffused to the target 10.SELECTED DRAWING: Figure 2

Description

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

  Conventionally, boron neutron capture therapy (BNCT) using a boron compound is known as a neutron capture therapy for irradiating a neutron beam to kill cancer cells. In boron neutron capture therapy, neutrons are irradiated to boron that has been previously taken up by cancer cells, and the cancer cells are selectively destroyed by scattering of heavy charged particles generated thereby.

  As an apparatus used in such neutron capture therapy, for example, Patent Document 1 describes an apparatus that detects a dose of a charged particle beam irradiated on a target. A non-contact type current monitor is used as the detection unit. The non-contact type current monitor can detect the current of the charged particle beam without directly contacting the charged particle beam.

International Patent Publication 2012/014671 Pamphlet

  Here, the non-contact type current monitor as described above can grasp the total amount of current values, that is, the total amount of charged particle beam dose, but cannot grasp the dose distribution of charged particle beam. On the other hand, when a contact-type current monitor is used, the dose distribution of the charged particle beam can be grasped. However, a high-current charged particle beam is used in the neutron capture therapy apparatus. Accordingly, when a contact current monitor is irradiated with a charged particle beam with a large current, there arises a problem that the current monitor is deteriorated at an early stage.

  Therefore, an object of the present invention is to provide a neutron capture therapy apparatus and a neutron capture therapy target capable of grasping a dose distribution of a charged particle beam while suppressing deterioration of a detection unit.

  The neutron capture therapy apparatus according to the present invention is in contact with an accelerator that emits a charged particle beam, a neutron beam generation unit that is formed of a material that generates a neutron beam by being irradiated with the charged particle beam, and the charged particle beam. A detection unit that detects a current value of the charged particle beam, and the detection unit is in contact with the neutron beam generation unit.

  The neutron capture therapy apparatus according to the present invention includes a detection unit that detects a current value of a charged particle beam by contacting the charged particle beam. Since the detection unit directly contacts the charged particle beam and detects the current value, the dose distribution of the charged particle beam can be grasped by using the detection result of the detection unit. The detection unit is in contact with the neutron beam generation unit. Accordingly, even when the detection unit is irradiated with a charged particle beam of a large current and the detection unit generates heat, the heat of the detection unit is diffused to the neutron beam generation unit. Thereby, a detection part can be cooled. As described above, the dose distribution of the charged particle beam can be grasped while suppressing the deterioration of the detection unit.

  In the neutron capture therapy apparatus, the detection unit may be disposed inside the neutron beam generation unit. Accordingly, since the detection unit is surrounded by the neutron generation unit, the diffusibility of the heat generated by the detection unit to the neutron generation unit is improved.

  In the neutron capture therapy apparatus, the detection unit includes a conductor part and an insulating part that covers the periphery of the conductor part, and the conductor part may be insulated from the neutron beam generation part. Thereby, a conductor part and a neutron beam production | generation part can be insulated by an insulation part.

  The neutron capture therapy apparatus further includes a scanning unit that scans the charged particle beam and irradiates the neutron beam generation unit, and the detection unit extends in a first direction that intersects an irradiation axis direction of the charged particle beam. You may provide a extending | stretching part and the 2nd extending | stretching part extended | stretched in the 2nd direction which cross | intersects an irradiation axis direction and a 1st direction. Thereby, the detection part can detect a charged particle beam over the wide range of a neutron beam production | generation part by the 1st extending | stretching part and 2nd extending | stretching part which are extended | stretched in a mutually different direction.

  The target for neutron capture therapy according to the present invention is a solid shape neutron capture therapy target formed of a material that generates a neutron beam when irradiated with a charged particle beam, and is in contact with the charged particle beam. A detection unit that detects a current value of the charged particle beam and is in contact with the solid-state neutron capture therapy target;

  According to the neutron capture therapy target according to the present invention, it is possible to obtain the same operations and effects as those of the neutron capture therapy apparatus described above.

  ADVANTAGE OF THE INVENTION According to this invention, the neutron capture therapy apparatus which can grasp | ascertain the dose distribution of a charged particle beam, and the target for neutron capture therapy can be provided, suppressing deterioration of a detection part.

It is the schematic which shows the neutron capture therapy apparatus which concerns on embodiment of this invention. It is a perspective view which shows the structure of the target which concerns on this embodiment. It is sectional drawing along the III-III line | wire shown in FIG.2 (b). It is a schematic diagram for demonstrating the detection of the dose of a charged particle beam by a detection part. It is a graph which shows the electric current value detected by the 1st extending | stretching part and the 2nd extending | stretching part.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

First, taking the neutron capture therapy apparatus 1 according to the embodiment of the present invention as an example, an outline of the neutron capture therapy apparatus 1 will be described with reference to FIG. A neutron capture therapy device 1 shown in FIG. 1 is a device that performs cancer treatment using boron neutron capture therapy (BNCT). In the neutron capture therapy apparatus 1, for example, a neutron beam N is irradiated to a tumor of a patient (irradiated body) 50 to which boron ( ¹⁰ B) is administered.

  The neutron capture therapy apparatus 1 includes an accelerator 2. The accelerator 2 accelerates charged particles such as negative ions and emits a charged particle beam R. The accelerator 2 is configured by, for example, a cyclotron. In the present embodiment, the charged particle beam R is a proton beam generated by stripping charges from negative ions. The accelerator 2 generates a charged particle beam R having a beam radius of 40 mm and 60 kW (= 30 MeV × 2 mA), for example. The accelerator is not limited to a cyclotron, and may be a synchrotron, a synchrocyclotron, a linac, an electrostatic accelerator, or the like.

  The charged particle beam R emitted from the accelerator 2 is sent to the neutron beam generation unit M. The neutron beam generation unit M includes a beam duct 9 and a target (neutron beam generation unit, neutron capture therapy target) 10. The charged particle beam R emitted from the accelerator 2 passes through the beam duct 9 and travels toward the target 10 disposed at the end of the beam duct 9. A plurality of quadrupole electromagnets 4 and a scanning electromagnet (scanning unit) 6 are provided along the beam duct 9. The plurality of quadrupole electromagnets 4 adjust the beam axis of the charged particle beam R using, for example, an electromagnet.

  The scanning electromagnet 6 scans the charged particle beam R and controls irradiation of the charged particle beam R to the target 10. The scanning electromagnet 6 controls the irradiation position of the charged particle beam R with respect to the target 10.

  The neutron capture therapy apparatus 1 generates a neutron beam N by irradiating the target 10 with the charged particle beam R, and emits the neutron beam N toward the patient 50. The neutron capture therapy apparatus 1 includes a target 10, a shield 8, a moderator 39, and a collimator 20.

  The target 10 generates a neutron beam N when irradiated with the charged particle beam R. The target 10 is a solid member formed of a material that generates a neutron beam when irradiated with a charged particle beam. Specifically, the target 10 is made of, for example, beryllium (Be), lithium (Li), tantalum (Ta), or tungsten (W), and has a disk-like solid shape with a diameter of, for example, 160 mm. Note that the target 10 is not limited to a disk shape, and may have another shape.

  A cooling member 120 is connected to the target 10. The cooling member 120 has, for example, a plurality of grooves on a contact surface that contacts the target 10, and cools the target 10 by flowing a cooling fluid through the grooves.

  The moderator 39 decelerates the neutron beam N generated by the target 10 (decreases the energy of the neutron beam N). The moderator 39 may have a laminated structure including a layer 39A that mainly decelerates fast neutrons contained in the neutron beam N and a layer 39B that mainly decelerates epithermal neutrons contained in the neutron beam N. .

  The shield 8 shields the generated neutron beam N and the gamma rays generated by the generation of the neutron beam N so as not to be emitted to the outside. The shield 8 is provided so as to surround the moderator 39. The upper part and the lower part of the shield 8 extend upstream of the charged particle beam R from the moderator 39.

  The collimator 20 shapes the irradiation field of the neutron beam N, and has an opening 20a through which the neutron beam N passes. The collimator 20 is a block-shaped member having an opening 20a at the center, for example.

  Next, a detailed configuration of the target 10 according to the present embodiment will be described with reference to FIGS. As shown in FIG. 2, the target 10 includes a detection unit 100 that detects a current value of the charged particle beam R by contacting the charged particle beam R. In the present embodiment, the detection unit 100 intersects the first extending unit 100A extending in the first direction D1 intersecting the irradiation axis direction D3 of the charged particle beam R, the irradiation axis direction, and the first direction D1. And a second extending portion 100B extending in the second direction D2. The first direction D1 is a direction orthogonal to the irradiation axis direction D3, and the second direction D2 is a direction orthogonal to the irradiation axis direction D3 and the first direction D1. As described above, the linear first extending portion 100A extending straight in the first direction D1 and the linear second extending portion 100B extending straight in the second direction D2 are combined, so that the target 10 includes a detection unit 100 in a cross shape.

  In the present embodiment, the detection unit 100 is provided inside the target 10. The first extending portion 100 </ b> A has a portion 100 </ b> Aa disposed inside the target 10. Further, the first extending portion 100 </ b> A has portions 100 </ b> Ab that are drawn to the outside of the target 10 from both sides of the portion 100 </ b> Aa disposed inside the target 10. The second extending portion 100 </ b> B has a portion 100 </ b> Ba disposed inside the target 10. Further, the second extending portion 100 </ b> B has portions 100 </ b> Bb that are drawn to the outside of the target 10 from both sides of the portion 100 </ b> Ba disposed inside the target 10. In the example shown in FIG. 2, the first extending portion 100A is curved so as to avoid the second extending portion 100B at a location where the first extending portion 100A and the second extending portion 100B intersect. However, the second extending portion 100B may be curved, and both the first extending portion 100A and the second extending portion 100B may be curved. Alternatively, the position in the irradiation axis direction D3 inside the target 10 is different between the first extending portion 100A and the second extending portion 100B, whereby the first extending portion 100A and the second extending portion 100B interfere with each other. It may be arranged so as not to.

  The target 10 is divided into two in the irradiation axis direction D3 in order to arrange the detection unit 100 inside. The target 10 is configured by sandwiching the detection unit 100 between the first piece 10A and the second piece 10B. The first piece 10A and the second piece 10B have a groove 110A and a groove 110B for disposing the detection unit 100, respectively. The groove 110A of the first piece 10A has a portion extending straight in the first direction D1 and a second direction for arranging the second extending portion 100B in order to arrange the first extending portion 100A. And a portion extending straight to D2. The groove portion 110B of the second piece 10B has a portion extending straight in the first direction D1 in order to dispose the first extending portion 100A and a second direction in order to dispose the second extending portion 100B. And a portion extending straight to D2. Note that only one of the first piece 10A and the second piece 10B may have a groove.

  Next, the shape of the first extending portion 100A of the detection unit 100 and the shape of the target 10 corresponding to the shape will be described in more detail with reference to FIG. In addition, since the 2nd extending | stretching part 100B has the structure of the same meaning as 100 A of 1st extending | stretching parts, description is abbreviate | omitted. As illustrated in FIG. 3, the first extending portion 100 </ b> A of the detection unit 100 includes a conductive conductor portion 101 and an insulating portion 102 that surrounds the conductor portion 101. The conductor portion 101 is a linear member through which current flows when in contact with the charged particle beam R. The conductor 101 passes a current having a current value corresponding to the dose of the charged particle beam R in contact therewith. The conductor 101 is made of a material such as copper or aluminum, for example. The insulating portion 102 functions as a member that insulates between the conductor portion 101 and the target 10. The insulating unit 102 has a function of diffusing heat generated in the conductor unit 101 to the target 10 when the charged particle beam R is irradiated. The insulating part 102 covers the conductor part 101 over the entire collection. In the present embodiment, the conductor part 101 has a circular cross section. The insulating part 102 is formed in an annular shape surrounding the conductor part 101. However, the cross-sectional shapes of the conductor portion 101 and the insulating portion 102 are not particularly limited, and may be formed in an elliptical shape or a polygonal shape, for example.

  The groove portion 110A of the first piece 10A of the target 10 and the groove portion 110B of the second piece 10B have a shape corresponding to the outer shape of the first extending portion 100A, that is, the outer shape of the insulating portion 102 by being combined with each other. In the present embodiment, the groove 110A and the groove 110B have a semicircular cross-sectional shape. The groove 110A and the groove 110B are in contact with the first extending portion 100A, that is, the outer peripheral surface of the insulating portion 102. In addition, when the external shape of 100 A of 1st extending | stretching parts is changed, the shape of 110 A of groove parts and the groove part 110B may be suitably changed according to the said shape. Further, the first extending portion 100 </ b> A may not be in contact with the target 10 over the entire area inside the target 10, and a part of the region may be separated from the target 10.

  Next, the detection of the dose of the charged particle beam R by the detection unit 100 will be described in detail with reference to FIG. As shown in FIG. 4, a portion 100 </ b> Ab drawn out from the target 10 in the first extending portion 100 </ b> A is connected to the measuring unit 150 via the terminal 105 and the wiring 106. Further, the portion 100 </ b> Bb drawn out from the target 10 in the second extending portion 100 </ b> B is connected to the measuring unit 150 through the terminal 105 and the wiring 106.

  A range of the charged particle beam R irradiated to the target 10 is an irradiation range E. Here, it is assumed that the shape of the irradiation range E is a perfect circle. The scanning electromagnet 6 (see FIG. 1) scans the charged particle beam R so that the irradiation range E of the charged particle beam R draws a circular or spiral trajectory on the target 10. That is, the irradiation range E does not indicate the entire region through which the charged particle beam R can pass by scanning with the scanning electromagnet 6, but the charged particle beam R is irradiated when scanning of the charged particle beam R is stopped. Refers to the range to be As described above, the first extending portion 100A and the second extending portion 100B are arranged in a cross shape. That is, the first extending portion 100A or the second extending portion 100B is disposed around the central axis at 90 ° intervals. Therefore, when the charged particle beam R is scanned, the charged particle beam R comes into contact with the first extending portion 100A or the second extending portion 100B at a constant period.

  The upper graph in FIG. 5 shows the current value detected by the first extending portion 100A, and the lower graph shows the current value detected by the second extending portion 100B. For example, in FIG. 4, the charged particle beam R is a portion on the left side of the center of the target 10 in the second extending portion 100B, a portion on the upper side of the target 10 in the first extending portion 100A, and the second extending portion. The part on the right side of the center of the target 10 in the part 100B and the part on the lower side of the center of the target 10 in the first extending part 100A are contacted in this order. In this case, as shown in FIG. 5, the current value in the lower graph rises (peak P1), the current value in the upper graph rises (peak P2), the current value in the lower graph rises (peak P3), and the upper graph Current value rises (peak P4). In addition, the time between each peak becomes a fixed pitch.

  The manner in which the current value rises will be described by taking as an example a state in which the charged particle beam R is in contact with the portion of the first extending portion 100A above the center of the target 10. When the charged particle beam R is scanned in a circular orbit and the vicinity of the edge of the irradiation range E of the charged particle beam R comes into contact with the first extending portion 100A (state shown by “B” in FIG. 4), the first stretching is performed. The current value detected by the unit 100A rises (see, for example, the portion indicated by time t1 in FIG. 5). Here, in the charged particle beam R, the dose per unit area increases toward the center of the irradiation range E, and the dose per unit area decreases toward the edge. Further, the charged particle beam R has a larger irradiation area in contact with the first extending portion 100A toward the center of the irradiation range E, and a smaller irradiation area in contact with the first extending portion 100A toward the edge. Therefore, in a state where the edge of the irradiation range E is in contact with the first extending portion 100A, the detected current value is small. As scanning of the charged particle beam R further proceeds from this state, the current value gradually increases. When the center of the irradiation range E reaches the position of the first extending portion 100A (state indicated by “A” in FIG. 4), the current value detected by the first extending portion 100A becomes the peak P2 (FIG. 5). Thereafter, when the irradiation range E is further scanned, the current value gradually decreases.

  Therefore, the measurement unit 150 of the detection unit 100 can grasp the dose distribution of the charged particle beam R based on the waveform of the current value as shown in FIG. Further, the measurement unit 150 can monitor whether the irradiation with the charged particle beam R is normally performed based on the dose distribution of the charged particle beam R. Moreover, the measurement part 150 can grasp | ascertain the dose distribution in each position in which the peaks P1-P4 are formed. For example, when the current value at the peak does not reach a predetermined value and the mountain formed by the rise of the current value is too wide, or the current value at the peak is too high and the rise of the current value When the mountain formed by is too narrow, the measurement unit 150 can detect that there is an abnormality in the adjustment of the dose distribution within the irradiation range E. When the pitch of each peak is not constant, the measurement unit 150 can detect that there is an abnormality in scanning of the charged particle beam by the scanning electromagnet 6.

  Next, operations and effects of the neutron capture therapy apparatus 1 and the target 10 according to the present embodiment will be described.

  The neutron capture therapy apparatus 1 according to the present embodiment includes a detection unit 100 that detects a current value of the charged particle beam R by contacting the charged particle beam R. Since the detection unit 100 directly contacts the charged particle beam R and detects the current value, the dose distribution of the charged particle beam R can be grasped by using the detection result of the detection unit 100. Further, the detection unit 100 is in contact with the target 10. Accordingly, even when the detection unit 100 is irradiated with a charged particle beam with a large current and the detection unit 100 generates heat, the heat of the detection unit 100 is diffused to the target 10. Further, a cooling member 120 is connected to the target 10. Therefore, the cooling member 120 can cool the detection unit 100 via the target 10. Thereby, the detection part 100 can be cooled. As described above, the dose distribution of the charged particle beam R can be grasped while suppressing the deterioration of the detection unit 100.

  In the neutron capture therapy apparatus 1, the detection unit 100 may be disposed inside the target 10. Thereby, since the detection unit 100 is surrounded by the target 10, the diffusibility of the heat generated by the detection unit 100 to the target 10 is improved.

  In the neutron capture therapy apparatus 1, the detection unit 100 includes a conductor part 101 and an insulating part 102 that covers the periphery of the conductor part 101, and the conductor part 101 may be insulated from the target 10. Thereby, the conductor part 101 and the target 10 can be insulated by the insulating part 102.

  The neutron capture therapy apparatus 1 further includes a scanning electromagnet 6 that scans the charged particle beam R and irradiates the target 10, and the detection unit 100 extends in a first direction D1 that intersects the irradiation axis direction of the charged particle beam R. 100A of 1st extending | stretching, and 2nd extending | stretching part 100B extended | stretched to the 2nd direction D2 which cross | intersects the irradiation axis direction D3 and the 1st direction D1 may be provided. Accordingly, the detection unit 100 can detect the charged particle beam R over a wide range of the target 10 by the first extending unit 100A and the second extending unit 100B extending in different directions.

  The target 10 according to the present embodiment is a solid-shaped target 10 formed of a material that generates a neutron beam N when irradiated with a charged particle beam R. A detection unit 100 that detects the current value of the line R and is in contact with the target 10 is provided.

  According to the target 10 according to the present embodiment, it is possible to obtain the same actions and effects as those of the neutron capture therapy apparatus 1 described above.

  The present invention is not limited to the embodiment described above.

  For example, in the above-described embodiment, the detection unit is configured to be able to detect at 90 ° intervals around the center axis of the target by two extending units, but the detection unit may be configured in any manner. For example, it is good also as a structure which can be detected at intervals of 90 degrees or less around the central axis of a target by using two or more extending parts. Moreover, a detection part may be comprised by arrange | positioning so that it may mutually be parallel, without crossing several extending | stretching parts. The detection unit may be configured by arranging a plurality of extending portions in a mesh shape. Or a detection part may be comprised only by one extending | stretching part. Moreover, the electric wire with an insulating part which comprises a detection part does not need to extend | stretch in a predetermined direction, and may be arrange | positioned so that it may bend within a target.

  Moreover, in the above-mentioned embodiment, although the detection part was provided in the inside of a target, as long as it is contacting with the target, you may arrange | position so that it may be exposed from a target.

  Further, in the above-described embodiment, in the first extending portion 100A, the portion 100Ab is pulled out from the target 10 from both ends in the first direction D1, and is connected to the measuring unit 150, respectively. Instead, the first extending part 100A may be connected to the measuring part 150 only at one end side in the first direction D1. Further, the second extending portion 100B may also be connected to the measuring unit 150 only at one end side in the second direction D2.

  DESCRIPTION OF SYMBOLS 1 ... Neutron capture therapy apparatus, 2 ... Accelerator, 6 ... Scanning electromagnet (scanning part) 10 ... Target (neutron beam generation part, target for neutron capture therapy), 100 ... Detection part, 100A ... 1st extending | stretching part, 100B ... Second extending portion, 101 ... conductor portion, 102 ... insulating portion.

Claims (5)

An accelerator that emits a charged particle beam;
A neutron beam generator formed of a material that generates a neutron beam by being irradiated with the charged particle beam;
A detection unit that detects a current value of the charged particle beam by contacting the charged particle beam,
The detection unit is a neutron capture therapy device in contact with the neutron beam generation unit.   The neutron capture therapy apparatus according to claim 1, wherein the detection unit is disposed inside the neutron beam generation unit. The detection unit includes a conductor part and an insulating part covering the periphery of the conductor part,
The neutron capture therapy apparatus according to claim 1, wherein the conductor part is insulated from the neutron beam generation part. A scanning unit that scans the charged particle beam and irradiates the neutron beam generation unit;
The detector is
A first extending portion extending in a first direction intersecting the irradiation axis direction of the charged particle beam;
The neutron capture therapy apparatus according to any one of claims 1 to 3, further comprising a second extending portion extending in a second direction intersecting the irradiation axis direction and the first direction. A solid shape neutron capture therapy target formed of a material that generates a neutron beam when irradiated with a charged particle beam,
A neutron capture therapy target comprising: a detection unit that detects a current value of the charged particle beam by contacting the charged particle beam and is in contact with the neutron capture therapy target.

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