JP2009189725A - Neutron beam irradiation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a neutron beam irradiation apparatus easily positioning a neutron beam outlet in a collimater and an irradiation target whereby irradiation precision can be increased. <P>SOLUTION: The neutron beam irradiation apparatus 1, related to an apparatus of irradiation with a neutron beam to an affected part T of a patient P, is equipped with a mounting table 2 for mountting the patient P, a deceleration device 3 for decelerating the neutron beam, and a collimater 4 for convergence of the neutron beam. The collimater 4 is held on a cover 11 through a collimater holder 10, and the mounting table 2 and the collimater 4 are set forth in such a way as movable against the deceleration device 3 along a neutron beam outlet direction F. The neutron beam irradiation apparatus 1 is further equipped with a CR imaging part 22 imaging an X ray image of the affected part T from a space between the collimater 4 and the deceleration device 3 after the deceleration device 3 is separated from the mounting table 2 and the collimater 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a neutron beam irradiation apparatus.

Conventionally, as a neutron beam irradiation apparatus, what was described in Unexamined-Japanese-Patent No. 11-57043 is known. The neutron beam irradiation apparatus described in this publication has a deflection magnet that distributes accelerated charged particles from an accelerator in a plurality of directions, a target that generates neutrons by the impact of accelerated charged particles, and a mounting table on which an irradiated object is mounted. A collimator for converging neutrons, and a neutron moderator interposed between the target and the collimator. And the acceleration effect is aimed at by distributing the acceleration charged particle from an accelerator with a deflection magnet by a predetermined ratio, and adjusting the intensity of the neutron to irradiate.
Japanese Patent Laid-Open No. 11-57043

  However, in the above-described conventional neutron beam irradiation apparatus, the collimator, the moderator and the target are integrated. Therefore, after setting the irradiated object on the mounting table, the neutron outlet of the collimator from the rear side of the irradiated object And the positional relationship between the irradiation target and the irradiation target are confirmed. For this reason, there is a problem in that it is difficult to align the neutron outlet of the collimator and the irradiation target, and it is difficult to improve the irradiation accuracy.

  An object of the present invention is to provide a neutron beam irradiation apparatus that can easily align a neutron outlet of a collimator and an irradiation target and improve irradiation accuracy.

  A neutron beam irradiation apparatus according to the present invention is a neutron beam irradiation apparatus that irradiates a target to be irradiated with a neutron beam, a deceleration table including a mounting table on which the irradiation object is mounted and a moderator that decelerates neutrons. And a collimator that converges the neutrons decelerated by the speed reducer and extracts them to the mounting table side, and the collimator and the mounting table are provided so as to be movable relative to the speed reducing device. And

  In the neutron beam irradiation apparatus according to the present invention, the collimator and the mounting table are provided so as to be relatively movable with respect to the speed reduction device. Therefore, the collimator and the mounting table are separated from or brought close to the speed reduction device. can do. Therefore, after the collimator and the mounting table are separated from the speed reducer, the positional relationship between the collimator neutron outlet and the irradiation target can be confirmed from the opposite side of the mounting table. As a result, the alignment between the neutron outlet of the collimator and the irradiation target can be easily performed, and the irradiation accuracy can be improved. And after aligning both, a collimator and a mounting base are made to approach a reduction gear, and it becomes possible to irradiate a neutron beam to an irradiation target with high precision by emitting a neutron from a reduction gear.

In the neutron beam irradiation apparatus according to the present invention, it is preferable that the collimator and the mounting table are provided so as to be movable along the neutron extraction direction.
In this way, the collimator and the mounting table are separated from the decelerator along the neutron extraction direction, and after aligning the collimator neutron outlet and the irradiation target from the opposite side of the mounting table, Since the speed reducer can be brought closer by simply sliding the collimator and mounting table in the direction opposite to the extraction direction, it is possible to maintain the alignment state between the neutron outlet and the irradiation target. Generation of misalignment can be prevented.

In the neutron beam irradiation apparatus according to the present invention, when the collimator and the mounting table are separated from the speed reduction device, an X-ray image of the irradiation target of the irradiated object mounted on the mounting table is captured between the collimator and the speed reduction device. It is preferable to further include an imaging unit.
In this way, since the positional relationship between the neutron outlet of the collimator and the irradiation target can be confirmed based on the X-ray image of the irradiation target, the two can be easily aligned and the irradiation accuracy can be improved. It becomes easy.

In the neutron beam irradiation apparatus according to the present invention, it is preferable that the apparatus further includes a collimator holder that supports the collimator, and the collimator holder is provided with a recess for accommodating the tip of the speed reducer therein.
In this way, the alignment between the collimator and the speed reducer can be performed easily and accurately, so that the irradiation accuracy can be further improved.

  An object of the present invention is to provide a neutron beam irradiation apparatus that can easily align a neutron outlet of a collimator and an irradiation target and improve irradiation accuracy.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a neutron beam irradiation apparatus according to the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the neutron beam irradiation apparatus 1 is an apparatus that irradiates a diseased part (irradiation target) T inside a patient (irradiated body) P with neutron beams. This neutron beam irradiation apparatus 1 is mainly composed of a mounting table 2 on which a patient P is mounted, a speed reducing device 3 that decelerates neutrons, and a collimator 4 provided between the mounting table 2 and the speed reducing device 3. Yes.

  The mounting table 2 includes a seat part 5 on which the patient P sits, a backrest 6 standing on the seat part 5, and a head holding part 7 installed on the upper end of the backrest 6. The mounting table 2 is supported by the support portion 8 and is movable in the vertical direction, the horizontal direction, and the front-back direction.

  The speed reduction device 3 emits neutrons by irradiating an ion beam to a target 15 (see FIG. 3) installed therein, and after the generated neutrons are decelerated, it is emitted to the patient P side. The speed reducer 3 is slidably supported on the base 9. The shielding wall W is formed from concrete and prevents unnecessary radiation to the patient P. The tip 3 a of the reduction gear 3 penetrates the shielding wall W and enters the collimator holder 10.

  The collimator 4 is disposed between the mounting table 2 and the collimator holder 10 and converges the neutrons emitted from the speed reducer 3 and extracts them in the neutron extraction direction F. As shown in FIG. 2, the collimator 4 is formed in a rectangular parallelepiped shape from a polyethylene material containing lithium fluoride. In the center of the collimator 4, a neutron outlet 4 a having a size that matches the shape of the affected part T is provided. Neutrons emitted from the speed reducer 3 are irradiated to the affected part T of the patient P through the neutron outlet 4a.

  The collimator 4 is fixed to the cover 11 via a collimator holder 10 that supports the collimator 4. The collimator holder 10 is made of aluminum, and a recess 10 a that matches the shape of the tip 3 a of the speed reducer 3 is provided on the side facing the speed reducer 3. The cover 11 is made of glass fiber reinforced plastic, and the side adjacent to the speed reduction device 3 is in contact with the shielding wall W. The tip 3 a of the speed reduction device 3 enters the recess 10 a of the collimator holder 10 and is covered with the collimator holder 10 and the cover 11. In order to prevent leakage of radiation or the like, it is preferable that the gap between the tip 3a and the collimator holder 10 is lead shielded.

  The collimator 4 and the mounting table 2 are provided so as to be movable integrally with the reduction gear 3. Specifically, the cover 11 for fixing the collimator 4 and the collimator holder 10 and the support portion 8 for supporting the mounting table 2 are fixed to the moving base 25 installed below them, and the moving base 25 is The moving means 26 provided inside allows reciprocal movement in the neutron extraction direction F and in the opposite direction. The collimator 4 and the mounting table 2 are separated from the speed reduction device 3 or approach the speed reduction device 3 as the moving base 25 reciprocates. Examples of the moving means 26 include an LM guide (Linear Motion Guide) suitable for linear motion.

  The neutron beam irradiation apparatus 1 includes a CR (Computed Radiography) imaging unit 22 that captures an X-ray image of the affected part T of the patient P. The CR imaging unit 22 is disposed behind the X-ray tube 23 installed above the cover 11 disposed between the mounting table 2 and the reduction gear 3 and the head holding unit 7 of the mounting table 2. The imaging plate 24 includes an image display unit (not shown) that processes and displays an X-ray image.

  As shown in FIG. 3, the speed reduction device 3 has a cylindrical shape, a cylindrical target accommodating portion 12 that extends along the central axis L direction, and a speed reduction that is disposed at the central position and extends in the central axis L direction. It is mainly comprised from the material 13, and the reflecting material 14 which surrounds the moderator 13 and the target accommodating part 12 from the circumference.

  The target 15 is accommodated in the target accommodating portion 12, and a material such as beryllium, lithium, tantalum, or tungsten is used. When the ion beam is irradiated, neutrons are generated in all directions, and some of the generated neutrons enter the moderator 13. Examples of ion beams include protons and deuterons.

  The moderator 13 includes a first moderator layer 16, a second moderator layer 17, a third moderator layer 18, and a fourth moderator layer 19 made of different materials, and has high energy generated from the target 15. Among neutrons, incident neutrons are decelerated to low energy neutrons called heat or heat. These deceleration layers 16 to 19 are each formed in a disk shape, and the first deceleration layer 16, the second deceleration layer 17, and the third deceleration mode are formed along the central axis L direction from the neutron incident side to the emission side. The layer 18 and the fourth deceleration layer 19 are arranged in this order.

  The first deceleration layer 16 is made of lead, and the second deceleration layer 17 is made of iron. The second deceleration layer 17 is formed larger than the outer diameter of the first deceleration layer 16. The third deceleration layer 18 is made of metal aluminum and is formed to be larger than the outer diameter of the second deceleration layer 17. The fourth deceleration layer 19 is obtained by melting a raw material having calcium fluoride, and is formed to have the same outer diameter as that of the third deceleration layer 18. Since the outer diameter of the moderator 13 configured in this way increases from the neutron incident side to the exit side along the central axis L direction, the neutron scattering range is expanded by the collision with the moderator 13. By increasing the cross-sectional area of the moderator 13, the neutron moderating effect can be improved.

  The reflective material 14 is made of lead, and includes five reflective layers 14A to 14E each formed in an annular shape. This reflecting material 14 reflects neutrons inside and prevents them from leaking outside. The reflection layers 14A to 14E are arranged in order from the neutron incident side to the emission side along the central axis L direction, and the adjacent reflection layers 14A to 14E are fixed in close contact with each other.

  The reflective layers 14A to 14E are formed in a concavo-convex shape so that the adjacent reflective layers 14A to 14E are fitted to each other. For example, in the reflective layer 14C, a concave portion for fitting the convex portion of the reflective layer 14B is provided on the side adjacent to the reflective layer 14B, and the concave portion of the reflective layer 14D is fitted on the side adjacent to the reflective layer 14D. Convex portions are provided for insertion. If it does in this way, when assembling reflective layer 14A-14E, since adjacent reflective layer 14A-14E is positioned easily, an assembly operation is simplified. Furthermore, since the boundary between adjacent reflective layers 14A to 14E is formed in an uneven shape by being formed in such an uneven shape, neutrons pass through the boundary as compared with the case where the boundary is formed in a straight line. Can be surely prevented from leaking outside.

  A shield member 20 made of polyethylene containing lithium fluoride and a shield member 21 made of lead are provided at the emission end of the reduction gear 3. The shielding material 20 is formed in an annular shape, is in close contact with the fourth deceleration layer 19 and is fixed to the reflective layer 14E to shield unnecessary neutrons. The shielding material 21 is formed in a disc shape, is disposed outside the shielding material 20, and is fixed to the reflective layer 14 </ b> E via the shielding material 20. The shielding material 21 serves to shield γ rays and the like generated from the target 15.

  Hereinafter, the operation of the neutron beam irradiation apparatus 1 will be described with reference to FIG.

  First, as shown in FIG. 1, in the approaching state where the mounting table 2 and the collimator 4 approach the speed reduction device 3, the patient P faces the collimator 4 and sits on the mounting table 2. Here, the approaching state refers to a state in which the cover 11 is in contact with the shielding wall W and the distal end portion 3a of the speed reduction device 3 enters the recess 10a of the collimator holder 10.

  Next, based on the treatment plan examined separately beforehand, both are aligned while confirming the positional relationship between the neutron extraction port 4a of the collimator 4 and the affected part T. For example, when a positional shift occurs between the two, alignment is performed by moving the position of the patient P up and down and left and right using the support portion 8 of the mounting table 2.

  Next, after positioning, the mounting base 2 and the cover 11 are separated from the speed reducer 3 by moving the moving base 25 in the neutron extraction direction F as shown in FIG. Next, the X-ray tube 23 of the CR imaging unit 22 is lowered to irradiate the affected part T of the patient P from between the speed reduction device 3 and the cover 11, and the image of the affected part T is recorded on the imaging plate 24. Then, the captured X-ray image of the affected part T is displayed on the image display unit of the CR imaging unit 22.

  After performing alignment and X-ray imaging of the neutron extraction port 4a of the collimator 4 and the affected part T, the X-ray tube 23 is raised, and the mounting table 2 and the cover 11 are brought close to the speed reduction device 3 using the moving base 25. . Next, the target 15 is irradiated with an ion beam to generate neutrons, and the affected part T is irradiated with neutron beams. The neutron beam then reacts with the boron compound previously taken into the affected area T to generate α rays, and the generated α rays selectively destroy the cells in the affected area T.

  In the neutron beam irradiation apparatus 1 configured as described above, since the mounting table 2 and the collimator 4 are provided so as to be movable with respect to the speed reduction device 3, the mounting table 2 and the collimator 4 are reduced. 3 can be separated from or approached. Therefore, after the mounting table 2 and the collimator 4 are separated from the speed reducer 3, the positional relationship between the neutron outlet 4a of the collimator 4 and the affected part T can be confirmed from the opposite side of the mounting table 2 with the collimator 4 interposed therebetween. It becomes possible. As a result, the alignment between the neutron outlet 4a of the collimator and the affected part T can be easily performed, and the irradiation accuracy can be improved. Then, after aligning the two, the collimator 4 and the mounting table 2 are brought close to the speed reducer 3 to emit neutrons from the speed reducer 3, so that the affected part T can be irradiated with neutron beams with high accuracy. It becomes.

  Moreover, since the mounting table 2 and the collimator 4 are provided so as to be movable along the neutron extraction direction F, the neutron extraction port 4a of the collimator 4 and the affected part T are aligned from the opposite side of the mounting table 2. After the operation, the mounting table 2 and the cover 11 can be brought close to the speed reducer 3 by simply sliding in the direction opposite to the neutron extraction direction F. Therefore, the alignment state between the neutron extraction port 4a of the collimator and the affected part T Therefore, it is possible to prevent the displacement of both due to movement. In addition, the collimator holder 10 is provided with a recess 10a for accommodating the tip 3a of the speed reducer 3 therein, so that when the speed reducer 3 and the collimator 4 are aligned, the recess 10a However, by accommodating the distal end portion 3a of the speed reducer 3, the positioning of both can be performed easily and accurately, and the irradiation accuracy can be further improved.

  Furthermore, the neutron beam irradiation apparatus 1 includes a CR imaging unit 22, and the CR imaging unit 22 is arranged between the cover 11 and the speed reduction device 3 when the mounting table 2 and the collimator 4 are separated from the speed reduction device 3. X-ray images of the affected part T can be taken. And since alignment with the neutron extraction opening 4a of the collimator 4 and the affected part T can be confirmed easily, it becomes easy to aim at the improvement of irradiation accuracy.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the ion beam was irradiated to the neutron generation target 15 as the neutron generation source. However, the neutron beam from the nuclear reactor is directly introduced without providing the target 15. May be.

  In the embodiment described above, the alignment between the neutron outlet 4 a and the affected part T is confirmed based on the X-ray image captured using the CR imaging unit 22, but the CR imaging unit 22 is not used. You may confirm alignment of both visually. Further, the movement of the mounting table 2 and the collimator 4 is not limited to the separation in the neutron extraction direction F. For example, the positional relationship between the neutron outlet 4a and the affected part T can be confirmed from the opposite side of the mounting table 2. Alternatively, the moving base 25 may be shifted in a direction orthogonal to the neutron extraction direction F, or the moving base 25 may be rotated about one corner of the moving base 25 to which the mounting table 2 and the collimator 4 are fixed.

It is the schematic which shows embodiment of the neutron beam irradiation apparatus which concerns on this invention. It is a perspective view which shows a collimator. It is a fragmentary sectional view of a reduction gear. It is the schematic explaining imaging of CR apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Neutron beam irradiation apparatus, 2 ... Mounting stand, 3 ... Deceleration apparatus, 3a ... Tip part, 4 ... Collimator, 4a ... Neutron extraction port, 10 ... Collimator holder, 10a ... Recessed part, 22 ... CR imaging part, P ... Patient (Irradiated body), T ... affected area (irradiation target), F ... neutron extraction direction.

Claims (4)

A neutron beam irradiation apparatus for irradiating a target with an neutron beam on an irradiation target,
A mounting table for mounting the irradiated object;
A speed reducer having a moderator for decelerating neutrons;
A collimator that converges the neutrons decelerated by the decelerator and takes them out to the mounting table side, and
2. The neutron beam irradiation apparatus according to claim 1, wherein the collimator and the mounting table are provided so as to be movable relative to the speed reducer.   The neutron beam irradiation apparatus according to claim 1, wherein the collimator and the mounting table are provided so as to be movable along a neutron extraction direction.   When the collimator and the mounting table are separated from the reduction device, an imaging unit that captures an X-ray image of an irradiation target of the irradiated object placed on the mounting table from between the collimator and the reduction device. The neutron beam irradiation apparatus according to claim 1, further comprising: The collimator holder which supports the said collimator is further provided, The said collimator holder is provided with the recessed part for accommodating the front-end | tip part of the said speed reducer in the inside. The neutron beam irradiation apparatus according to item 1.

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