JP5009278B2 - Beam dump - Google Patents

Description

  The present invention relates to a beam dump receiving a charged particle beam.

  For example, radiotherapy is highly evaluated in cancer treatment and the like. In particular, neutron capture therapy (BNCT), which has the possibility of selective treatment at the cellular level, has attracted attention. In this BNCT, cancer cells to be treated are preloaded with stable isotopes that generate heavy charged particles, and then irradiated with neutrons. Destroy selectively.

  In the radiotherapy apparatus, charged particles such as protons are accelerated using an accelerator such as a cyclotron. The high-energy ion beam extracted from the cyclotron is irradiated to a target that generates neutrons, and the generated neutrons are irradiated to cancer cells to be treated.

In this type of radiotherapy apparatus, the beam output is confirmed before treatment. At this time, the beam extracted from the accelerator is removed from the normal trajectory at the time of treatment. Patent Document 1 discloses a beam stopper for causing a beam removed from a normal orbit to collide. By making the beam collide with the beam stopper, the energy of the beam is consumed. In the radiotherapy apparatus described in Patent Document 1, the beam collision position is appropriately changed to prevent a local temperature rise and improve the durability of the beam stopper.
JP-A-10-28742

  However, in the prior art described in the above-mentioned Patent Document 1, it is desired to further extend the life while preventing a local temperature rise by appropriately changing the collision position of the beam against the beam stopper.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a beam dump capable of improving the cooling capacity and extending the life.

  The beam dump according to the present invention is a beam dump having a beam receiving surface for receiving a charged particle beam, and a beam receiving portion having a beam receiving surface arranged to be inclined with respect to the charged particle beam, and radiation heat from the beam receiving surface. A radiant heat receiving portion having a radiant heat receiving surface, a first cooling portion that cools the beam receiving surface, and a second cooling portion that cools the radiant heat receiving surface.

  In such a beam dump, since the beam receiving surface that receives the charged particle beam is inclined with respect to the charged particle beam, the contact area between the charged particle beam and the beam receiving surface can be increased, Local temperature rise can be suppressed. Moreover, since it is the structure provided with the radiation heat receiving surface which receives the radiation heat from a beam receiving surface, a beam receiving surface can be cooled by absorbing the radiation heat of a beam receiving surface by a radiation heat receiving part. In addition, since the first cooling unit that cools the beam receiving surface and the second cooling unit that cools the radiation heat receiving surface are provided, the beam receiving surface is cooled and the radiation heat receiving surface is cooled to radiate heat. The absorption efficiency of can be improved. Accordingly, it is possible to improve the cooling capacity, suppress the temperature rise of the beam receiving surface, and prevent the beam receiving surface from being consumed.

  Moreover, it is preferable that the position of the beam receiver and the radiation heat receiver can be exchanged. Thereby, when the beam receiving portion is consumed, the life can be extended by replacing the radiant heat receiving portion and the beam receiving portion.

  Moreover, it is preferable that the beam receiver and the radiant heat receiver are arranged symmetrically so that their positions can be reversed.

  ADVANTAGE OF THE INVENTION According to this invention, the beam dump which can aim at the improvement of a cooling capability and lifetime can be provided.

  Hereinafter, a preferred embodiment of a beam dump according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a BNCT apparatus provided with a beam dump according to an embodiment of the present invention, and FIGS. 2 to 4 are diagrams showing the beam dump.

  A BNCT apparatus 1 shown in FIG. 1 is an apparatus for performing cancer treatment using neutron capture therapy (BNCT). The BNCT apparatus 1 includes a cyclotron 2, and the cyclotron 2 accelerates charged particles such as protons to generate a proton beam (hereinafter referred to as “beam”) B. For example, the cyclotron 2 has a capability of generating a beam of 60 kW (= 30 MeV × 2 mA).

  The beam B extracted from the cyclotron 2 passes through the first beam line L1 and reaches the switching device 3 such as a deflection electromagnet capable of changing the beam direction. The beam direction of the beam B is changed by the switching device 3 that can change the beam direction, passes through the second beam line L2, and reaches the irradiation device 4.

  The irradiation device 4 includes a treatment bed on which a patient is placed. The irradiation device 4 is provided with a target device that emits a beam and generates neutrons. The generated neutron is irradiated to the patient.

  In the BNCT apparatus 1, the output of the beam B is confirmed before treatment or the like. At this time, the beam B extracted from the cyclotron 2 is removed from the normal trajectory at the time of treatment. The BNCT apparatus 1 includes a beam dump 10 for causing the beam B removed from the normal orbit to collide. The beam B that has passed through the switching device 3 passes through the third beam line L3 and reaches the beam dump 10. A cover 6 is provided around the beam dump 10.

  2 is a plan view of the beam dump, FIG. 3 is a sectional view taken along line III-III in FIG. 2, and FIG. 4 is a sectional view taken along line IV-IV in FIG. The axis extending in the beam traveling direction is the X axis, the axis extending in the width direction (vertical direction in FIG. 2) orthogonal to the X axis is the Y axis, and the axis orthogonal to the X axis and the Y axis is the Z axis. And

  As shown in FIGS. 3 and 4, the beam dump 10 includes an upper plate (beam receiving portion) 11 that receives the beam B and a lower plate (radiation heat receiving portion) 21 that receives the radiation heat from the upper plate 11. Yes. As shown in FIG. 3, the upper plate 11 is disposed to be inclined with respect to the beam B (X axis), and the lower plate 21 is disposed along the X axis.

  The upper plate 11 includes an activation preventing member 12 that forms a beam receiving surface 12a that is disposed to be inclined with respect to the beam B, and a cooling plate 13 (first cooling unit) that cools the activation preventing member 12. I have. The upper plate 11 is inclined such that the front side (beam incidence side) is disposed above the back side.

  The activation preventing member 12 has a flat plate shape, and is made of, for example, a graphite plate material. The activation preventing member 12 constitutes a beam receiving surface 12a on which the beam B collides. As the activation preventing member 12, a material having a predetermined heat resistance performance and exhaust heat performance and having a property of not being activated can be used.

  As shown in FIGS. 2 and 4, the activation preventing member 12 is thinner on both sides in the Y-axis direction than the central portion. Bolt holes are formed in the four corners of the activation preventing member 12. The activation preventing member 12 is fixed to the cooling plate 13 by bolts 43 and is in surface contact with the cooling plate 13.

  The cooling plate 13 has a flat plate shape and is formed of, for example, a copper plate. The cooling plate 13 is larger in area and thicker than the activation preventing member 12.

  Inside the cooling plate 13, an inlet-side main water channel 14, a cooling water channel 15, and an outlet-side main water channel 16 are formed as distribution channels through which the cooling water flows. An inlet-side main water channel 14 is formed on one side of the cooling plate 13, and an outlet-side main water channel 16 is formed on the other side of the cooling plate 13. The inlet-side main water channel 14 and the outlet-side main water channel 16 extend in the X-axis direction, and the plurality of cooling water channels 15 extend in the Y-axis direction between the inlet-side main water channel 14 and the outlet-side main water channel 16.

  An inlet pipe L5 is connected to the inlet-side main water channel 14, and an outlet pipe L6 is connected to the outlet-side main water channel 16. The cooling water channel 15 communicates with the inlet-side main water channel 14 and the outlet-side main water channel 16. The cooling water channel 15 is disposed on the radiation preventing member 12 side in the Z-axis direction. The opening formed when the cooling water channel 15 is drilled is closed by a plug 17.

  The lower plate 21 includes a radiant heat receiving plate 22 having a radiant heat receiving surface 22 a that receives radiant heat from the beam receiving surface 12 a of the upper plate 11, and a cooling plate (second cooling unit) 23 that cools the radiant heat receiving plate 22. ing. The radiant heat receiving plate 22 has a flat plate shape, and is made of, for example, a graphite plate material. The radiant heat receiving plate 22 constitutes a radiant heat receiving surface that receives the radiant heat from the beam receiving surface 22a on which the beam B collides. As the radiant heat receiving plate 22, a material having predetermined heat resistance performance and exhaust heat performance can be used.

  As shown in FIG. 4, the radiant heat receiving plate 22 is thinner on both sides in the Y-axis direction than the center portion. Bolt holes are formed in the four corners of the radiation heat receiving plate 22. The radiation heat receiving plate 22 is fixed to the cooling plate 23 by bolts 44 and is in surface contact with the cooling plate 23.

  The cooling plate 23 has a flat plate shape and is formed of, for example, a copper plate. The cooling plate 23 is larger in area and thicker than the radiant heat receiving plate 22.

  Inside the cooling plate 23, an inlet-side main water channel 24, a cooling water channel 25, and an outlet-side main water channel 26 are formed as distribution channels through which the cooling water flows. An inlet-side main water channel 24 is formed on one side of the cooling plate 23, and an outlet-side main water channel 26 is formed on the other side of the cooling plate 23. The inlet-side main water channel 24 and the outlet-side main water channel 26 extend in the X-axis direction, and the plurality of cooling water channels 25 extend between the inlet-side main water channel 24 and the outlet-side main water channel 26 in the Y-axis direction.

  An inlet pipe L5 is connected to the inlet-side main water channel 24, and an outlet pipe L6 is connected to the outlet-side main water channel 26. The cooling water channel 25 communicates with the inlet-side main water channel 24 and the outlet-side main water channel 26. The cooling water channel 25 is disposed on the radiation preventing member 22 side in the Z-axis direction. The opening formed when the cooling water channel 25 is drilled is closed by a plug 27.

  Further, the beam dump 10 includes a front wall 31, a back wall 32, and a side wall 33. As shown in FIG. 3, the front wall 31 has an opening (beam introduction port) 31a for allowing the beam B to pass therethrough. The third beam line L3 communicates with the opening 31a, and the beam B that has passed through the third beam line L3 passes through the opening 31a and can collide with the activation preventing member 12.

  The front wall 31, the back wall 32, and the side walls 33, 33 are joined to each other, and form a rectangular frame in plan view. The upper end of the side wall 32 is formed so that the front side is located above the back side.

  The upper plate 11 is fixed to the upper end portions of the front wall 31 and the back wall 32 by bolts 41. The upper plate 11 is in contact with the upper ends of the front wall 31, the rear wall 32, and the side walls 33, 33, and is disposed to be inclined with respect to the X axis.

  The lower plate 21 is fixed to the lower ends of the front wall 31 and the back wall 32 by bolts 42. The lower plate 21 is in contact with the lower end of the front wall 31, the rear wall 32, and the side walls 33, 33, and is disposed along the X-axis direction. Note that the lower plate 21 may be disposed to be inclined with respect to the X axis.

  As shown in FIG. 4, a plurality of bolt holes are formed on the outer surface of the lower plate 21. A base plate 51 is fixed to the outer surface of the lower plate 21 by bolts 45. The base plate 51 is supported from below by a support column 52, and the support column 52 is fixed to a floor or the like by a fixing unit 53.

  In the beam dump 10 thus configured, first, cooling water is injected. The cooling water is injected into the inlet-side main water channels 14 and 24 through the inlet pipe L5. The cooling water injected into the inlet-side main water channel 14 passes through the cooling water channels 15 and 25 and reaches the outlet-side main water channels 16 and 26. The cooling water that has reached the outlet-side main water channel 16 is discharged out of the beam dump 10 through the outlet pipe L6. While the beam dump 10 is in use, cooling water is injected and discharged.

  The beam B extracted from the cyclotron 2 passes through the first beam line L1 and reaches the switching device 3. At the time of treatment, the beam direction is changed by the switching device 3, passes through the second beam line L 2, and the beam B reaches the irradiation device 4. On the other hand, when the patient does not irradiate the beam B, the beam B extracted from the cyclotron 2 reaches the switching device 3 and then passes as it is, passes through the third beam line L3, and reaches the beam dump 10. To do.

  The beam B that has reached the beam dump 10 travels straight in the X-axis direction and enters the beam dump 10. The beam B travels straight as it is and collides with the activating member 12 disposed so as to be inclined with respect to the X axis. In other words, the beam B collides with the surface of the activation member 12 while being inclined at a predetermined angle. Thereby, compared with the case where it collides perpendicularly with respect to the beam receiving surface 12a, the contact area of the beam B and the beam receiving surface 12a can be enlarged. As a result, the local temperature rise of the activation member 12 can be prevented. The contact portion between the beam B and the activation member 12 is, for example, an ellipse as shown in FIG.

  The heat of the beam B is transmitted to the activation member 12 and transmitted to the cooling plate 13. The heat transmitted to the cooling plate 13 is transmitted to the cooling water passing through the cooling water channel 15. Thereby, the activation member 12 can be cooled suitably. In addition, the heat transfer efficiency between the activation member 12 and the cooling plate 13 can be improved by increasing the contact area between the beam B and the beam receiving surface 12a.

  In the beam dump 10, the radiation heat from the activation member 12 is absorbed by the radiation heat receiving plate 22. The activation member 12 absorbs radiation heat from the beam and the activation member 12. The radiating member 12 is cooled by the radiation heat receiving plate 22 absorbing the radiation heat.

  The heat transmitted to the radiation heat receiving plate 22 is transmitted to the cooling plate 23. The heat transmitted to the cooling plate 13 is transmitted to the cooling water passing through the cooling water channel 25. Thereby, the radiation heat receiving plate 22 can be suitably cooled. By cooling the radiation heat receiving plate 22, the radiation heat absorption efficiency of the radiation heat receiving plate 22 can be improved.

  According to such a beam dump 10, since the activation member 12 is arranged at an inclination, the collision area with the beam B is expanded, the local temperature rise is suppressed, and the activation member 12 is consumed. Can be suppressed. As a result, the life of the beam dump 10 can be extended.

  Moreover, since the beam dump 10 is provided with the radiation heat receiving plate 22 and can absorb the radiation heat from the activation member 12, the activation member 12 is cooled. Therefore, the activation member 12 can be suitably cooled to suppress the activation member 12 from being consumed. As a result, a beam dump in which the cooling capacity is improved and the lifetime of the activation member 12 is extended can be realized.

  As mentioned above, although this invention was concretely demonstrated based on the embodiment, this invention is not limited to the said embodiment. For example, the upper plate 11 and the lower plate 21 may have the same structure and can be replaced with each other. For example, the base plate 51 for fixing the base plate 51 may be provided on the outer surface of the upper plate 11. If comprised in this way, when the activation member 12 is exhausted, the upper plate 11 and the lower plate 21 are replaced so that what has been used as the radiant heat receiving plate 22 of the lower plate 21 becomes the beam receiver that receives the beam B. Can be used as a surface.

  Moreover, it is good also as a structure provided with the inversion apparatus for arrange | positioning the upper board 11 and the lower board 21 symmetrically, and exchanging a mutual position. Thus, the positions of the upper plate 11 and the lower plate 21 can be easily exchanged.

  Moreover, it is good also as a structure provided with a radiation heat receiving surface by arrange | positioning a graphite material etc. to the inner surface of the front wall 31, the back wall 32, and the side wall 33. FIG.

  Further, the upper plate 11 may be configured not to be inclined with respect to the Y axis, or may be configured to be inclined with respect to the Y axis. The beam receiving surface may be a curved surface. Further, a cooling water channel may be provided in the activation member 12 and the radiation heat receiving plate 22.

It is a schematic block diagram of the BNCT apparatus provided with the beam dump which concerns on embodiment of this invention. It is a top view of the beam dump concerning the embodiment of the present invention. It is sectional drawing which follows the III-III line of FIG. It is sectional drawing which follows the IV-IV line of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... BNCT apparatus, 2 ... Cyclotron, 3 ... Switching apparatus, 4 ... Irradiation apparatus, 6 ... Cover, 10 ... Beam dump, 11 ... Upper plate (beam receiving part), 12 ... Radiation prevention member, 12a ... Beam receiving surface , 13 ... Cooling plate (first cooling section), 14 ... Inlet side main water channel, 15 ... Cooling water channel, 16 ... Outlet side main water channel, 17 ... Plug, 21 ... Lower plate (radiation heat receiving portion), 22 ... Radiation heat receiving portion Plate, 22a ... Radiant heat receiving surface, 23 ... Cooling plate (second cooling part), 24 ... Inlet side main water channel, 25 ... Cooling channel, 26 ... Outlet side main water channel, 27 ... Plug, 31 ... Front wall, 31a ... Opening portion (beam introduction port), 32 ... back wall, 33 ... side wall, 41-45 ... bolt, 51 ... base plate, 52 ... column, 53 ... fixing part, L1-L3 ... beam line, L5 ... inlet pipe, L6 ... Exit piping, B ... B .

Claims (3)

In a beam dump with a beam receiving surface that receives a charged particle beam,
A beam receiving portion having the beam receiving surface arranged to be inclined with respect to the charged particle beam;
A radiation heat receiving portion having a radiation heat receiving surface for receiving radiation heat from the beam receiving surface;
A first cooling section for cooling the beam receiving surface;
A second cooling section for cooling the radiation heat receiving surface ,
The beam dump is characterized in that the beam receiving portion is provided so that a central axis of the charged particle beam is located on the beam receiving surface .   2. The beam dump according to claim 1, wherein the beam receiving portion and the radiation heat receiving portion can be exchanged with each other.   The beam dump according to claim 1 or 2, wherein the beam receiving portion and the radiation heat receiving portion are arranged symmetrically so that their positions can be reversed.

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