JP7175184B2 - Radiation reduction structure - Google Patents

Radiation reduction structure Download PDF

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JP7175184B2
JP7175184B2 JP2018239338A JP2018239338A JP7175184B2 JP 7175184 B2 JP7175184 B2 JP 7175184B2 JP 2018239338 A JP2018239338 A JP 2018239338A JP 2018239338 A JP2018239338 A JP 2018239338A JP 7175184 B2 JP7175184 B2 JP 7175184B2
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radiation
shielding structure
shielding
recessed
seismic isolation
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JP2020101432A (en
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琢真 能任
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Shimizu Corp
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Description

本発明は、放射線発生装置が設置された放射線照射室の外側に設けた空間（例えば、免震層などの空間）における放射線管理区域を小さくする放射線低減構造を提供する。 The present invention provides a radiation reduction structure that reduces the radiation controlled area in a space (for example, a space such as a seismic isolation layer) provided outside a radiation irradiation room in which a radiation generator is installed.

例えば、Ｘ線などの放射線の照射室においては、放射線が当該照射室から外部に漏洩することを低減する構造が採用されている。 For example, in an irradiation chamber for radiation such as X-rays, a structure is adopted to reduce leakage of radiation from the irradiation chamber to the outside.

例えば、特許文献１（特開２００４－４５３３８号公報）では、通路に屈曲部分（１２）を設けることにより、照射室の被照射物から反射されて外部に漏洩する放射線の線量を低減する技術が開示されている。
特開２００４－４５３３８号公報 For example, Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2004-45338) discloses a technique for reducing the dose of radiation that leaks to the outside after being reflected from an object to be irradiated in an irradiation chamber by providing a curved portion (12) in the passage. disclosed.
JP-A-2004-45338

電子リニアック（直線加速器）等の放射線発生装置が設置された放射線照射室では、管理区域外への放射線の漏洩を抑え、管理区域境界の実効線量を法令で定める値以下にするため、コンクリートや鉄を使った厚い遮蔽壁が設けられる。 In the radiation irradiation room where radiation generators such as electron linacs (linear accelerators) are installed, concrete and iron are used to suppress the leakage of radiation outside the controlled area and to keep the effective dose at the boundary of the controlled area below the value stipulated by law. A thick shielding wall using

ところで、免震構造の普及により、放射線照射室が免震層の直上に作られる案件が増えている。放射線照射室を免震層の直上に設けるとき、免震層の一部（放射線照射室の直下付近）を放射線管理区域としてしまい、放射線発生装置の稼働中においては当該管理区域内への立ち入りを制限することで、免震層に放射線管理区域を設けない場合に比べ、照射室の床部の遮蔽性能を下げ、建設コストを下げることが考えられる。 By the way, due to the spread of seismic isolation structures, the number of cases where the radiation irradiation room is built directly above the seismic isolation layer is increasing. When the radiation irradiation room is set up directly above the seismic isolation layer, part of the seismic isolation layer (near the area immediately below the radiation irradiation room) is designated as a radiation controlled area, and no one is allowed to enter the controlled area while the radiation generator is in operation. It is conceivable that the restriction will lower the shielding performance of the floor of the irradiation room and lower the construction cost compared to the case where the radiation control area is not provided in the seismic isolation layer.

上記のように、放射線照射室直下の免震層内に放射線管理区域を設ける施設について、免震層のメンテナンス等により当該管理区域内に人が立ち入る場合、放射線発生装置の稼働状況とスケジュールを調整する必要がある。そこで、免震層内の放射線管理区域については可能な限り小さいことが望ましいが、これまで、免震層内の当該管理区域を小さくするための放射線低減構造については提案がされておらず問題であった。 As described above, for facilities with a radiation controlled area in the seismic isolation layer directly below the radiation irradiation room, if people enter the controlled area due to maintenance of the seismic isolation layer, etc., the operating status and schedule of the radiation generator will be adjusted. There is a need to. Therefore, it is desirable that the radiation controlled area in the seismic isolation layer is as small as possible. there were.

この発明は、上記課題を解決するものであって、本発明に係る放射線遮蔽構造は、照射方向へ放射線を照射する放射線発生装置が設置された設置空間の周囲に設けられ、前記放射線発生装置で発生する放射線を遮蔽する第１遮蔽構造物と、
前記第１遮蔽構造物の下方に設けられる第２遮蔽構造物と、を有する放射線低減構造であって、
前記第１遮蔽構造物と前記第２遮蔽構造物との間には、免震装置が設けられ、
前記第２遮蔽構造物は、前記第１遮蔽構造物と空間を介して対向し、
前記放射線発生装置の照射部に対して前記照射方向の下流側に位置する箇所に、前記照射方向の下流側へ凹んだ凹部を有することを特徴とする。
The present invention is intended to solve the above problems, and a radiation shielding structure according to the present invention is provided around an installation space in which a radiation generator that emits radiation in an irradiation direction is installed, and the radiation generator emits radiation. a first shielding structure that shields the generated radiation;
a second shielding structure provided below the first shielding structure, the radiation reducing structure comprising:
A seismic isolation device is provided between the first shielding structure and the second shielding structure,
The second shielding structure faces the first shielding structure with a space therebetween,
It is characterized in that a concave portion recessed downstream in the irradiation direction is provided at a location located downstream in the irradiation direction with respect to the irradiation section of the radiation generator .

また、本発明に係る放射線遮蔽構造は、前記凹部には、開口部がすぼんだ形状を有することを特徴とする。
Further, in the radiation shielding structure according to the present invention, the concave portion has a shape in which the opening portion is sunken .

また、本発明に係る放射線遮蔽構造は、前記第１遮蔽構造物と前記第２遮蔽構造物との間は、人が通行可能となっていることを特徴とする。
Moreover, the radiation shielding structure according to the present invention is characterized in that a person can pass between the first shielding structure and the second shielding structure .

本発明に係る放射線低減構造は、少なくとも第２遮蔽構造物で放射線照射範囲に該当する箇所は、他の箇所より凹んだ凹構造部を有しており、このような放射線低減構造によれば、例えば、放射線照射室の下に設けた免震層における管理区域を小さくすることができる。 In the radiation reduction structure according to the present invention, at least a portion of the second shielding structure corresponding to the radiation irradiation range has a recessed structure portion recessed from other portions. According to such a radiation reduction structure, For example, it is possible to reduce the controlled area in the seismic isolation layer provided under the radiation irradiation room.

本発明の実施形態に係る放射線低減構造１の適用先の一つである免震層を下部に有する放射線照射室２の一例を示す図である。It is a figure which shows an example of the radiation irradiation room 2 which has a seismic isolation layer in the lower part which is one of the application places of the radiation reduction structure 1 which concerns on embodiment of this invention. 本発明の実施形態に係る放射線低減構造１を説明する図である。It is a figure explaining the radiation reduction structure 1 which concerns on embodiment of this invention. 本発明の実施形態に係る放射線低減構造１による効果を説明する図である。It is a figure explaining the effect by the radiation reduction structure 1 which concerns on embodiment of this invention. 本発明の第２の実施形態に係る放射線低減構造１の概要を説明する模式図である。It is a schematic diagram explaining the outline|summary of the radiation reduction structure 1 which concerns on the 2nd Embodiment of this invention. 本発明の実施形態に係る放射線低減構造１の他の適用例を説明する図である。It is a figure explaining other examples of application of radiation reduction structure 1 concerning an embodiment of the present invention.

以下、本発明の実施の形態を図面を参照しつつ説明する。図１は本発明の実施形態に係る放射線低減構造１の適用先の一つである免震層を下部に有する放射線照射室２の一例を示す図である。 BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an example of a radiation irradiation room 2 having a seismic isolation layer underneath, which is one of the applications of the radiation reduction structure 1 according to the embodiment of the present invention.

放射線照射室２には、放射線発生装置が設置されている。本実施形態においては、このような放射線発生装置における放射線源３のみを示すこととする。放射線発生装置の一例としては、Ｘ線照射を行う電子リニアック（直線加速器）を挙げることできる。ただし、本発明に係る放射線低減構造１は、放射線源３としてＸ線を照射するものを含め、α線、β線、γ線、イオンなどの各放射線を照射する線源にも対応することができるものである。 A radiation generator is installed in the radiation irradiation room 2 . In this embodiment, only the radiation source 3 in such a radiation generator is shown. An example of a radiation generator is an electron linac (linear accelerator) that emits X-rays. However, the radiation-reducing structure 1 according to the present invention can also be compatible with radiation sources that irradiate radiation such as α-rays, β-rays, γ-rays, and ions, including those that irradiate X-rays as the radiation source 3. It is possible.

ここで、放射線発生装置が設置される空間である放射線照射室２を、設置空間Ａとして定義する。また、放射線源３は、放射線照射範囲Ｒに対して放射線を照射するものとする。放射線照射室２においては、放射線照射範囲Ｒ内に治療台５が載置され、当該治療台５上で患者（不図示）が放射線照射による治療を受けることが想定されている。 Here, the radiation irradiation room 2, which is the space in which the radiation generator is installed, is defined as an installation space A. As shown in FIG. Moreover, the radiation source 3 shall irradiate the radiation irradiation range R with radiation. In the radiation irradiation room 2, a treatment table 5 is placed within a radiation irradiation range R, and it is assumed that a patient (not shown) receives radiation treatment on the treatment table 5. FIG.

設置空間Ａの下部には、放射線源３で発生する放射線を遮蔽するために配されている第１遮蔽構造物Ｂが設けられる。この第１遮蔽構造物Ｂとしては、一般的にはコンクリートや鉄などが用いられる。この第１遮蔽構造物Ｂの外側には、免震装置７が収容された免震層などの空間が配される。この免震層などの空間を、外側空間Ｃとして定義する。この外側空間Ｃの外周囲には、免震装置７の基礎となると共に、放射線の遮蔽役としても機能する第２遮蔽構造物Ｄが設けられている。 Below the installation space A, a first shielding structure B is arranged to shield the radiation generated by the radiation source 3 . As the first shielding structure B, concrete, iron, or the like is generally used. Outside the first shielding structure B, a space such as a seismic isolation layer in which the seismic isolation device 7 is housed is arranged. A space such as this seismic isolation layer is defined as an outer space C. As shown in FIG. A second shielding structure D is provided around the outside space C to serve as a base for the seismic isolation device 7 and also function as a radiation shield.

本発明に係る放射線低減構造１は、放射線源３が配されてなる設置空間Ａと、この設置空間Ａから離れる順に、第１遮蔽構造物Ｂと、主として空洞の外側空間Ｃと、第２遮蔽構造物Ｄとがレイアウトされた構造物に適用されることが前提となる。 The radiation reduction structure 1 according to the present invention includes an installation space A in which a radiation source 3 is arranged, a first shielding structure B, a mainly hollow outer space C, and a second shielding structure in order away from the installation space A. It is assumed that the structure D is applied to the laid out structure.

以上のような前提の下、本発明に係る放射線低減構造１では、第２遮蔽構造物Ｄにおいて凹構造部１０を設けることによって、外側空間Ｃにおける実効線量を低減させるようにしている。このような凹構造部１０を有する本発明に係る構造物について、図１に示した従来の構造物との相違に基づいて説明する。 Under the above premise, in the radiation reduction structure 1 according to the present invention, the effective dose in the outer space C is reduced by providing the concave structure 10 in the second shielding structure D. A structure according to the present invention having such a concave structure 10 will be described based on differences from the conventional structure shown in FIG.

図２は本発明の実施形態に係る放射線低減構造１を説明する図であり、図２（Ａ）は従来の放射線照射室２周辺の構造を示しており、図２（Ｂ）は本発明に係る放射線低減構造１が適用された放射線照射室２周辺の構造を示している。なお、図において免震装置７については図示省略している。 2A and 2B are diagrams for explaining a radiation reduction structure 1 according to an embodiment of the present invention, FIG. 2A shows the structure around a conventional radiation irradiation chamber 2, and FIG. The structure around a radiation irradiation room 2 to which such a radiation reduction structure 1 is applied is shown. Note that the seismic isolation device 7 is omitted from the drawing.

本発明に係る放射線低減構造１は、図２（Ｂ）に示すように、少なくとも第２遮蔽構造物Ｄにおいて放射線照射範囲Ｒに該当する箇所（両矢印に示される箇所）は、他の箇所より凹んだ凹構造部１０を有することを特徴としている。第２遮蔽構造物Ｄが他の箇所より凹んでいる凹構造部１０は、通常の高さの床の底面より低い底面を有する構造を言う。 In the radiation reduction structure 1 according to the present invention, as shown in FIG. 2(B), at least a portion corresponding to the radiation irradiation range R (a portion indicated by a double-headed arrow) in the second shielding structure D is It is characterized by having a concave structure 10 which is recessed. The recessed structure 10, in which the second shielding structure D is recessed from other parts, refers to a structure having a bottom surface lower than the bottom surface of a normal floor.

設置空間Ａから放射線源３により放射線を照射すると、第１遮蔽構造物Ｂを透過した放射線のうち、一部は第１遮蔽構造物Ｂ内で散乱し、外側空間Ｃに広がるが、第１遮蔽構造物Ｂを透過した放射線は、第２遮蔽構造物Ｄにおける床の窪みである凹構造部１０を通してさらに下方側の底面に到達する。さらに、床面に到達した放射線は、凹構造部１０の内部で一部が反射を繰り返し、減衰され、外側空間Ｃにおける線量を低減させることができる。 When radiation is emitted from the installation space A by the radiation source 3, part of the radiation transmitted through the first shielding structure B is scattered within the first shielding structure B and spreads to the outer space C, but the first shielding structure Radiation transmitted through the structure B passes through the recessed structure 10, which is a recess in the floor of the second shielding structure D, and reaches the lower bottom surface. Further, part of the radiation reaching the floor is repeatedly reflected inside the concave structure 10 and attenuated, so that the dose in the outer space C can be reduced.

なお、凹構造部１０には、放射線を比較的通しやすいグレーチング等を設置することで、足場を設けることもできる。 A scaffolding can be provided in the recessed structure 10 by installing a grating or the like through which radiation can pass relatively easily.

本発明に係る放射線低減構造１の凹構造部１０による実効線量の低減効果についてモンテカルロ計算によるシミュレーションにより評価を行った。計算コードとしては、３次元モンテカルロ計算コードＭＣＮＰ５を用いた。 The effect of reducing the effective dose by the concave structure portion 10 of the radiation reducing structure 1 according to the present invention was evaluated by simulation using Monte Carlo calculation. A three-dimensional Monte Carlo calculation code MCNP5 was used as the calculation code.

当該計算において、放射線源３の第１遮蔽構造物Ｂの底面から２．２９５ｍとした。第１遮蔽構造物Ｂは普通コンクリート製とした。また、第１遮蔽構造物Ｂの厚さを１．６ｍ、外側空間Ｃの高さを１．０ｍとした。 In the calculation, the distance from the bottom surface of the first shielding structure B of the radiation source 3 was 2.295 m. The first shielding structure B was made of ordinary concrete. Also, the thickness of the first shielding structure B was set to 1.6 m, and the height of the outer space C was set to 1.0 m.

また、放射線源３からは、円錐状のＸ線ビームを、線源から１．０ｍ離れた地点で照射面積が０．１６ｍ2、同地点での水に対する吸収線量が３６０Ｇｙ／ｈになるように下向きに照射した。 A conical X-ray beam was emitted from the radiation source 3 so that the irradiation area was 0.16 m 2 at a point 1.0 m away from the radiation source, and the absorbed dose to water at the point was 360 Gy/h. Illuminated downward.

第２遮蔽構造物Ｄの床には遮蔽構造として、Ｘ線ビームの中心軸と中心を合わせた直径３ｍ、深さ０．４ｍの平面視円形状の凹構造部１０を設けた。 On the floor of the second shielding structure D, as a shielding structure, a recessed structure 10 having a diameter of 3 m and a depth of 0.4 m was provided as a shielding structure.

外側空間Ｃ内であって、第２遮蔽構造物Ｄの床上高さ０．５ｍ、Ｘ線ビームの軸からの水平距離（Ｈ）が４～９ｍの位置（×印にて図示した位置）にて、凹構造部１０が設けられていない従来の場合、本発明に係る放射線低減構造１の凹構造部１０が設けられた場合のそれぞれの実効線量を距離Ｈで１ｍ毎にモンテカルロ計算によって求めた。この結果を図３に示す。 In the outer space C, at a height of 0.5 m above the floor of the second shielding structure D, and at a horizontal distance (H) of 4 to 9 m from the axis of the X-ray beam (the position indicated by the x mark). Then, the effective dose in the case where the recessed structure 10 was not provided in the conventional case and in the case where the recessed structure 10 of the radiation reduction structure 1 according to the present invention was provided was obtained by Monte Carlo calculation for every 1 m at the distance H. . The results are shown in FIG.

図３に示すように、モンテカルロ計算で１ｍ毎に実効線量をそれぞれの場合で求めたところ、本発明に係る放射線低減構造１の凹構造部１０がありの場合は、凹構造部１０なしの場合に比べて平均して実効線量を２０％低減させることが確認できた。 As shown in FIG. 3, when the effective dose was calculated for each 1 m by Monte Carlo calculation in each case, the radiation reduction structure 1 according to the present invention with the recessed structure 10 had It was confirmed that the effective dose was reduced by 20% on average compared to .

以上のように、本発明に係る放射線低減構造１は、少なくとも第２遮蔽構造物Ｄで放射線照射範囲に該当する箇所は、他の箇所より凹んだ凹構造部１０を有しており、このような放射線低減構造１によれば、例えば、放射線照射室の下に設けた免震層における管理区域を小さくすることができる。 As described above, in the radiation reducing structure 1 according to the present invention, at least the portion corresponding to the radiation irradiation range of the second shielding structure D has the recessed structure portion 10 that is recessed from other portions. According to the radiation reduction structure 1, for example, the controlled area in the seismic isolation layer provided under the radiation irradiation room can be reduced.

次に、本発明の他の実施形態について説明する。図４は本発明の第２の実施形態に係る放射線低減構造１の概要を説明する模式図である。図４に示す実施形態では、凹構造部１０として、奥側（鉛直下方側）に、凹構造部１０の開口部１２の面積（Ｓ0）より、大きい面積（Ｓ1。ただし、Ｓ1＞Ｓ0）の断面部１５を有することを特徴としている。 Next, another embodiment of the present invention will be described. FIG. 4 is a schematic diagram for explaining the outline of the radiation reduction structure 1 according to the second embodiment of the present invention. In the embodiment shown in FIG. 4, the recessed structure 10 has an area (S 1 ) larger than the area (S 0 ) of the opening 12 of the recessed structure 10 on the far side (vertically downward side), where S 1 > S 0 ).

このような第２の実施形態の場合、第１遮蔽構造物Ｂを透過した放射線は、凹構造部１０の開口部１２を通してさらに奥の空間に到達する。断面部１５の広さが十分にあるとき、その内部で放射線が反射を繰り返し、減衰され、外側空間Ｃの線量を低減させることができる。第２の実施形態の場合、先の第１の実施形態に比べて、開口部１２の奥側に広い空間を有すると共に、断面部１５の面積（Ｓ1）が、開口部１２の面積（Ｓ0）より大きく設定されているため、外側空間Ｃにおけるより大きな線量低減効果を期待できる。 In the case of the second embodiment as described above, the radiation transmitted through the first shielding structure B reaches the deeper space through the opening 12 of the recessed structure 10 . When the cross section 15 is sufficiently wide, the radiation is repeatedly reflected and attenuated inside, and the dose in the outer space C can be reduced. In the case of the second embodiment, compared to the previous first embodiment, the space on the far side of the opening 12 is wider, and the area (S 1 ) of the cross section 15 is larger than the area (S 1 ) of the opening 12 . 0 ), a greater dose reduction effect in the outer space C can be expected.

第２の実施形態についても、実効線量をモンテカルロ計算によって求めた。図４において、平面視円形の開口部１２の直径は４．０ｍとし、平面視円形の断面部１５の直径は６．０ｍとした。 Also for the second embodiment, the effective dose was determined by Monte Carlo calculation. In FIG. 4, the diameter of the circular opening 12 in plan view was set to 4.0 m, and the diameter of the circular cross section 15 in plan view was set to 6.0 m.

第２遮蔽構造物Ｄの床上高さ０．５ｍ、Ｘ線ビームの軸からの水平距離（Ｈ）が４～９ｍの位置（×印にて図示した位置）にて、凹構造部１０が設けられていない従来の場合、第２の実施形態に係る放射線低減構造１の凹構造部１０が設けられた場合のそれぞれの実効線量を距離Ｈで１ｍ毎にモンテカルロ計算によって求めた。この結果、第２の実施形態に係る放射線低減構造１の凹構造部１０がある場合は、凹構造部１０なしの場合に比べて平均して実効線量を３７％低減させることが確認できた。 A recessed structure 10 is provided at a height of 0.5 m above the floor of the second shielding structure D and a horizontal distance (H) of 4 to 9 m from the axis of the X-ray beam (position indicated by x). In the case of the conventional case where the radiation reduction structure 1 according to the second embodiment is not provided, and in the case where the recessed structure portion 10 of the radiation reduction structure 1 according to the second embodiment is provided, the effective dose was obtained by Monte Carlo calculation every 1 m at the distance H. As a result, it was confirmed that when the concave structure 10 of the radiation reducing structure 1 according to the second embodiment was present, the effective dose was reduced by 37% on average compared to the case without the concave structure 10 .

外側空間Ｃの実効線量が、管理区域境界の実効線量限度１３００μＳｖ／３月の１／１０である１３０μＳｖ／３月となる範囲を平面視正方形で囲んで管理区域とした場合、以下のようになる。
・図２（Ａ）に示した凹構造部１０がないケースでは、Ｘ線ビーム中心軸から管理区域境界までの最短距離が６．３ｍ、正方形の面積が１５９ｍ2、面積比が１００％（本ケースを基準とする）。
・図２（Ｂ）に示した第１の実施形態に係る凹構造部１０を有するケースでは、Ｘ線ビーム中心軸から管理区域境界までの最短距離が５．８ｍ、正方形の面積が１３５ｍ2、面積比が８５％。
・図４に示した第２の実施形態に係る凹構造部１０を有するケースでは、Ｘ線ビーム中心軸から管理区域境界までの最短距離が５．４ｍ、正方形の面積が１１７ｍ2、面積比が７３％。 If the area where the effective dose in the outer space C is 130 μSv/3 months, which is 1/10 of the effective dose limit of 1300 μSv/3 months at the boundary of the controlled area, is defined as a controlled area by enclosing it with a square in plan view, it will be as follows. .
・In the case shown in FIG. 2A where there is no concave structure 10, the shortest distance from the center axis of the X-ray beam to the controlled area boundary is 6.3 m, the area of the square is 159 m 2 , and the area ratio is 100% (this case).
- In the case of having the recessed structure 10 according to the first embodiment shown in FIG . Area ratio is 85%.
- In the case of having the recessed structure 10 according to the second embodiment shown in FIG. 73%.

以上のように、特に第２の実施形態に係る放射線低減構造１によれば、凹構造部１０がない場合、管理区域の面積を２７％低減することができた。 As described above, according to the radiation reduction structure 1 according to the second embodiment, the area of the controlled area could be reduced by 27% without the recessed structure 10 .

次に、本発明に係る放射線低減構造１を他の状況に適用した例を示す。図５は本発明の実施形態に係る放射線低減構造１の他の適用例を説明する図である。図５は放射線照射室２周辺の構造の平面図を示している。 Next, an example in which the radiation reduction structure 1 according to the present invention is applied to another situation will be shown. FIG. 5 is a diagram illustrating another application example of the radiation reduction structure 1 according to the embodiment of the present invention. FIG. 5 shows a plan view of the structure around the radiation irradiation chamber 2. As shown in FIG.

これまで説明した本発明の適用例では、鉛直下方に向かって、放射線源３の設置空間Ａ、第１遮蔽構造物Ｂ、外側空間Ｃ、第２遮蔽構造物Ｄが順に配されていた。これに対して、図５に示す適用例では、放射線源３の設置空間Ａ、第１遮蔽構造物Ｂ、外側空間Ｃ、第２遮蔽構造物Ｄが順に水平方向に配されており、外側空間Ｃは通路２０として利用される空間に相当している。このような場合でも、第２遮蔽構造物Ｄにおける放射線照射範囲Ｒに該当する箇所には、他の箇所より凹んだ凹構造部１０を設けるようにする。このような図５に示す適用例では、通路２０における実効線量を低減することなどが可能となる。 In the application examples of the present invention described so far, the installation space A for the radiation source 3, the first shielding structure B, the outer space C, and the second shielding structure D are arranged in this order vertically downward. On the other hand, in the example of application shown in FIG. C corresponds to the space used as passage 20 . Even in such a case, a recessed structure 10 that is recessed from the other portions is provided in the portion corresponding to the radiation irradiation range R in the second shielding structure D. As shown in FIG. In such an application example shown in FIG. 5, it is possible to reduce the effective dose in the passage 20, and the like.

以上、本発明に係る放射線低減構造は、少なくとも第２遮蔽構造物で放射線照射範囲に該当する箇所は、他の箇所より凹んだ凹構造部を有しており、このような放射線低減構造によれば、例えば、放射線照射室の下に設けた免震層における管理区域を小さくすることができる。 As described above, in the radiation reduction structure according to the present invention, at least a portion of the second shielding structure corresponding to the radiation irradiation range has a concave structure recessed from other portions. For example, it is possible to reduce the controlled area in the seismic isolation layer provided under the radiation irradiation room.

１・・・放射線低減構造
２・・・放射線照射室
３・・・放射線源
５・・・治療台
７・・・免震装置
１０・・・凹構造部
１２・・・開口部
１５・・・断面部
２０・・・通路
Ａ・・・設置空間
Ｂ・・・第１遮蔽構造物
Ｃ・・・外側空間
Ｄ・・・第２遮蔽構造物
Ｒ・・・放射線照射範囲
Ｈ・・・Ｘ線ビーム中心軸からの水平距離 Reference Signs List 1... Radiation reduction structure 2... Radiation irradiation room 3... Radiation source 5... Treatment table 7... Seismic isolation device 10... Concave structure 12... Opening 15... Cross section 20 Passage A Installation space B First shielding structure C Outer space D Second shielding structure R Radiation irradiation range H X-ray Horizontal distance from beam center axis

Claims (3)

照射方向へ放射線を照射する放射線発生装置が設置された設置空間の周囲に設けられ、前記放射線発生装置で発生する放射線を遮蔽する第１遮蔽構造物と、
前記第１遮蔽構造物の下方に設けられる第２遮蔽構造物と、を有する放射線低減構造であって、
前記第１遮蔽構造物と前記第２遮蔽構造物との間には、免震装置が設けられ、
前記第２遮蔽構造物は、前記第１遮蔽構造物と空間を介して対向し、
前記放射線発生装置の照射部に対して前記照射方向の下流側に位置する箇所に、前記照射方向の下流側へ凹んだ凹部を有することを特徴とする放射線低減構造。 a first shielding structure provided around an installation space in which a radiation generator that emits radiation in an irradiation direction is installed and shields radiation generated by the radiation generator;
a second shielding structure provided below the first shielding structure, the radiation reducing structure comprising:
A seismic isolation device is provided between the first shielding structure and the second shielding structure,
The second shielding structure faces the first shielding structure with a space therebetween,
A radiation reducing structure characterized by having a concave portion recessed downstream in the irradiation direction at a location located downstream in the irradiation direction with respect to an irradiation section of the radiation generator . 前記凹部には、開口部がすぼんだ形状を有することを特徴とする請求項１に記載の放射線低減構造。 2. The radiation reducing structure according to claim 1, wherein the concave portion has a constricted opening. 前記第１遮蔽構造物と前記第２遮蔽構造物との間は、人が通行可能となっていることを特徴とする請求項１又は請求項２に記載の放射線低減構造。 3. The radiation reduction structure according to claim 1 , wherein a person can pass between said first shielding structure and said second shielding structure.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005049352A (en) 1998-06-23 2005-02-24 Titan Corp Article irradiation system having intermediate wall made of radiation shielding material within loop of conveyor system for conveying article
JP2017223088A (en) 2016-06-17 2017-12-21 株式会社大林組 Building
JP2018100550A (en) 2016-12-21 2018-06-28 大成建設株式会社 Medical base-isolated building comprising radiation irradiating chamber

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0355599U (en) * 1989-10-04 1991-05-29

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005049352A (en) 1998-06-23 2005-02-24 Titan Corp Article irradiation system having intermediate wall made of radiation shielding material within loop of conveyor system for conveying article
JP2017223088A (en) 2016-06-17 2017-12-21 株式会社大林組 Building
JP2018100550A (en) 2016-12-21 2018-06-28 大成建設株式会社 Medical base-isolated building comprising radiation irradiating chamber

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