JP2020101432A - Radiation reduction structure - Google Patents

Radiation reduction structure Download PDF

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JP2020101432A
JP2020101432A JP2018239338A JP2018239338A JP2020101432A JP 2020101432 A JP2020101432 A JP 2020101432A JP 2018239338 A JP2018239338 A JP 2018239338A JP 2018239338 A JP2018239338 A JP 2018239338A JP 2020101432 A JP2020101432 A JP 2020101432A
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radiation
shielding
space
outer space
shielding structure
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JP7175184B2 (en
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琢真 能任
Takuma Noto
琢真 能任
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Shimizu Construction Co Ltd
Shimizu Corp
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Shimizu Construction Co Ltd
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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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    • Y02E30/30—Nuclear fission reactors

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Abstract

To provide a radiation reduction structure which can reduce the management area of a seismic isolated layer under a radiation application room.SOLUTION: A radiation reduction structure (1) according to the present invention includes: a first shielding structure (B) around the set space (A) for shielding radiation generated from a radiation generator, the radiation generator being set in the set space to irradiate the radiation application range with radiation; an outer space (C) outside the first shielding structure (B); and a second shielding structure (D) around the outer space (C). At least a part of the second shielding structure (D) which corresponds to the radiation application range has a recessed structure part (10), more recessed than the other parts.SELECTED DRAWING: Figure 2

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 reducing structure that reduces a radiation control area in a space (for example, a space such as a seismic isolation layer) provided outside a radiation irradiation chamber 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 a radiation irradiation chamber for radiation such as X-rays, a structure that reduces the leakage of radiation from the irradiation chamber to the outside is adopted.

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, in Patent Document 1 (Japanese Patent Laid-Open No. 2004-45338), there is a technique of reducing the dose of radiation reflected from an object to be irradiated in the irradiation chamber and leaking to the outside by providing a bent portion (12) in the passage. It is disclosed.
JP, 2004-45338, A

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 a radiation irradiation room where a radiation generator such as an electronic linac (linear accelerator) is installed, concrete or iron is used in order to prevent radiation from leaking out of the controlled area and keep the effective dose at the boundary of the controlled area below the value specified by law. A thick shielding wall using is provided.

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 structure, the number of projects where the radiation irradiation room is made directly above the seismic isolation layer is increasing. When the radiation irradiation room is installed directly above the seismic isolation layer, part of the seismic isolation layer (around the area directly below the radiation irradiation room) becomes the radiation control area, and access to the control area is required while the radiation generator is operating. 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 no radiation control area is 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, regarding facilities that have a radiation control area within the seismic isolation layer directly below the radiation irradiation room, when a person enters the control area due to maintenance of the seismic isolation layer, the operation status and schedule of the radiation generator are adjusted. There is a need to. Therefore, it is desirable that the radiation control area in the seismic isolation layer be as small as possible, but so far no radiation reduction structure to reduce the control area in the seismic isolation layer has been proposed, and there is no problem. 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低減構造は、放射線照射範囲に対して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外周囲に設けられ、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遮蔽構造物の外側に配される外側空間と、前記外側空間の外周囲に設けられる第２遮蔽構造物と、からなる放射線低減構造であって、少なくとも前記第２遮蔽構造物で前記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することを特徴とする。 The present invention is to solve the above-mentioned problems, and a radiation reducing structure according to the present invention is provided in the outer periphery of an installation space in which a radiation generation device that irradiates a radiation irradiation range is installed. From a first shielding structure that shields the radiation generated by the radiation generation device, an outer space arranged outside the first shielding structure, and a second shielding structure provided around the outer space. The radiation reducing structure according to claim 1, wherein at least a portion corresponding to the radiation irradiation range in the second shielding structure has a concave structure portion that is recessed from other portions.

また、本発明に係る放射線低減構造は、前記凹構造部の奥側には、前記凹構造部の開口部の面積より、大きい面積の断面部を有することを特徴とする。 Further, the radiation reducing structure according to the present invention is characterized in that, on the inner side of the concave structure portion, a cross-sectional portion having an area larger than the area of the opening of the concave structure portion is provided.

また、本発明に係る放射線低減構造は、前記外側空間が免震層であることを特徴とする。 Further, the radiation reducing structure according to the present invention is characterized in that the outer space is a seismic isolation layer.

また、本発明に係る放射線低減構造は、前記外側空間が通路であることを特徴とする。 The radiation reducing structure according to the present invention is characterized in that the outer space is a passage.

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。 Radiation reduction structure according to the present invention, at least a portion corresponding to the radiation irradiation range in the second shielding structure has a concave structure portion recessed from the other portions, according to such a radiation reduction structure, For example, the control area in the seismic isolation layer provided below the radiation irradiation room can be made small.

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 chamber 2 which has the base isolation layer which is one of the application destinations of the radiation reduction structure 1 which concerns on embodiment of this invention in the lower part. 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 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 the other application example of the radiation reduction structure 1 which concerns on embodiment of this 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。 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 chamber 2 having a seismic isolation layer, which is one of the application destinations of the radiation reducing structure 1 according to the embodiment of the present invention, in a lower portion.

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 chamber 2. In the present embodiment, only the radiation source 3 in such a radiation generator will be shown. An example of the radiation generator is an electronic linac (linear accelerator) that performs X-ray irradiation. However, the radiation reducing structure 1 according to the present invention can be applied to a radiation source that emits each radiation such as α-rays, β-rays, γ-rays, and ions, including a radiation source 3 that emits X-rays. 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 chamber 2, which is a space in which the radiation generator is installed, is defined as an installation space A. Further, the radiation source 3 irradiates the radiation irradiation range R with radiation. In the radiation irradiation chamber 2, it is assumed that the treatment table 5 is placed within the radiation irradiation range R, and a patient (not shown) on the treatment table 5 is treated by radiation irradiation.

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 arranged to shield the radiation generated by the radiation source 3 is provided. As the first shielding structure B, concrete or iron is generally used. A space such as a seismic isolation layer in which the seismic isolation device 7 is housed is arranged outside the first shielding structure B. The space such as the seismic isolation layer is defined as the outer space C. A second shielding structure D, which serves as a basis for the seismic isolation device 7 and also functions as a radiation shield, is provided around the outer space C.

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 reducing 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, an outer space C mainly of a cavity, and a second shield in the order of being separated from the installation space A. It is premised 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, the radiation reducing structure 1 according to the present invention reduces the effective dose in the outer space C by providing the concave structure portion 10 in the second shielding structure D. A structure according to the present invention having such a concave structure portion 10 will be described based on a difference 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。 FIG. 2 is a diagram illustrating a radiation reducing structure 1 according to an embodiment of the present invention, FIG. 2(A) shows a structure around a conventional radiation irradiation chamber 2, and FIG. 2(B) shows the present invention. The structure around the radiation irradiation chamber 2 to which the radiation reducing structure 1 is applied is shown. The seismic isolation device 7 is not shown in the figure.

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 reducing structure 1 according to the present invention, as shown in FIG. 2(B), at least the portion corresponding to the radiation irradiation range R (the portion indicated by the double-headed arrow) in the second shielding structure D is more than other portions. It is characterized by having a recessed structure portion 10. The recessed structure portion 10 in which the second shielding structure D is recessed from other places is a structure having a bottom surface lower than the bottom surface of the floor of normal height.

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 the radiation source 3 irradiates the radiation from the installation space A, a part of the radiation transmitted through the first shield structure B is scattered in the first shield structure B and spreads to the outer space C, but the first shield The radiation transmitted through the structure B reaches the bottom surface on the further lower side through the concave structure portion 10 which is a recess of the floor in the second shielding structure D. Furthermore, the radiation that has reached the floor surface is partially reflected and attenuated inside the concave structure portion 10, and 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 scaffold can be provided in the concave structure 10 by installing grating or the like that allows radiation to pass through 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 by Monte Carlo calculation. As the calculation code, the three-dimensional Monte Carlo calculation code MCNP5 was used.

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 was set to 2.295 m from the bottom surface of the first shielding structure B of the radiation source 3. The first shielding structure B was made of ordinary concrete. Further, the thickness of the first shielding structure B was 1.6 m, and the height of the outer space C was 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。 In addition, the irradiation area of the conical X-ray beam from the radiation source 3 is 0.16 m 2 at a point 1.0 m away from the radiation source, and the absorbed dose to water at the point is 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 concave structure portion 10 having a circular shape in a plan view and having a diameter of 3 m and a depth of 0.4 m centered on the central axis of the X-ray beam was provided.

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 position where the height of the second shielding structure D on the floor is 0.5 m and the horizontal distance (H) from the axis of the X-ray beam is 4 to 9 m (the position shown by a cross mark). In the conventional case in which the concave structure portion 10 is not provided, the effective dose of each of the radiation reducing structure 1 according to the present invention in the case where the concave structure portion 10 is provided is calculated by Monte Carlo calculation for every 1 m at the distance H. .. The result is 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 case where the radiation reducing structure 1 according to the present invention has the concave structure portion 10 and the case where the concave structure portion 10 does not exist It was confirmed that the effective dose was reduced by 20% on average as compared with.

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 in the second shielding structure D has the concave structure portion 10 that is recessed from other portions. According to the radiation reduction structure 1, for example, the control area in the seismic isolation layer provided below the radiation irradiation chamber 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 illustrating an outline of the radiation reducing structure 1 according to the second embodiment of the present invention. In the embodiment shown in FIG. 4, as the recessed structure portion 10, an area (S 1 where S 1 >where S 1 >is larger than the area (S 0 ) of the opening 12 of the recessed structure portion 10 on the back side (vertically downward side). It is characterized by having a cross section 15 of 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 such a second embodiment, the radiation that has passed through the first shielding structure B reaches the space further inside through the opening 12 of the concave structure 10. When the width of the cross section 15 is sufficient, the radiation is repeatedly reflected and attenuated inside the cross section 15, and the dose in the outer space C can be reduced. In the case of the second embodiment, as compared with the first embodiment described above, there is a wider space on the inner side of the opening 12, and the area (S 1 ) of the cross section 15 is the area (S 1 ) of the opening 12. 0 ) Since it is set larger, a larger 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 in the second embodiment, the effective dose was obtained by Monte Carlo calculation. In FIG. 4, the diameter of the opening 12 having a circular shape in plan view was 4.0 m, and the diameter of the cross-sectional portion 15 having a circular shape in plan view was 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。 The recessed structure portion 10 is provided at a position where the height of the second shielding structure D on the floor is 0.5 m, and the horizontal distance (H) from the axis of the X-ray beam is 4 to 9 m (the position shown by X). In the case of the conventional case where the radiation reduction structure 1 according to the second embodiment is not provided, the effective dose of each is calculated by Monte Carlo calculation for every 1 m at the distance H. As a result, it was confirmed that the effective dose was reduced by 37% on the average when the concave structure portion 10 of the radiation reducing structure 1 according to the second embodiment was provided, compared with the case where the concave structure portion 10 was not provided.

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％。 When the effective dose of the outer space C is 130 μSv/March, which is 1/10 of the effective dose limit of 1300 μSv/March at the boundary of the control area, it is as follows when the area is surrounded by a square in plan view. ..
In the case where the concave structure portion 10 shown in FIG. 2(A) is not provided, the shortest distance from the X-ray beam center axis to the control area boundary is 6.3 m, the square area is 159 m 2 , and the area ratio is 100% (main Based on the case).
In the case having the concave structure portion 10 according to the first embodiment shown in FIG. 2B, the shortest distance from the X-ray beam central axis to the control area boundary is 5.8 m, and the square area is 135 m 2 , Area ratio is 85%.
In the case having the concave structure portion 10 according to the second embodiment shown in FIG. 4, the shortest distance from the X-ray beam central axis to the control area boundary is 5.4 m, the square area is 117 m 2 , and the area ratio is 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, particularly in the radiation reducing structure 1 according to the second embodiment, the area of the management area can be reduced by 27% when the concave structure portion 10 is not provided.

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, examples in which the radiation reducing structure 1 according to the present invention is applied to other situations will be shown. FIG. 5: is a figure explaining the other application example of the radiation reduction structure 1 which concerns on embodiment of this invention. FIG. 5 shows a plan view of the structure around the radiation irradiation chamber 2.

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 example of the present invention described so far, the installation space A of the radiation source 3, the first shield structure B, the outer space C, and the second shield structure D are arranged in this order in the vertically downward direction. On the other hand, in the application example shown in FIG. 5, the installation space A of the radiation source 3, the first shield structure B, the outer space C, and the second shield structure D are sequentially arranged in the horizontal direction. C corresponds to the space used as the passage 20. Even in such a case, the recessed structure portion 10 recessed from other parts is provided at a position corresponding to the radiation irradiation range R in the second shielding structure D. In the application example shown in FIG. 5, the effective dose in the passage 20 can be reduced.

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 reducing structure according to the present invention, at least the portion corresponding to the radiation irradiation range in the second shielding structure has the concave structure portion that is recessed from other portions. For example, for example, the control area in the seismic isolation layer provided below the radiation irradiation chamber can be reduced.

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 1... Radiation reduction structure 2... Radiation irradiation chamber 3... Radiation source 5... Treatment table 7... Seismic isolation device 10... Recessed structure 12... Opening 15... Cross section 20... Passage A... Installation space B... First shield structure C... Outer space D... Second shield structure R... Radiation irradiation range H... X-ray Horizontal distance from beam center axis

Claims (4)

放射線照射範囲に対して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外周囲に設けられ、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遮蔽構造物の外側に配される外側空間と、
前記外側空間の外周囲に設けられる第２遮蔽構造物と、からなる放射線低減構造であって、
少なくとも前記第２遮蔽構造物で前記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することを特徴とする放射線低減構造。 A first shielding structure which is provided on the outer periphery of an installation space in which a radiation generator for irradiating a radiation range is installed, and which shields radiation generated by the radiation generator.
An outer space arranged outside the first shielding structure,
A radiation reducing structure comprising: a second shielding structure provided on the outer periphery of the outer space;
At least a portion of the second shielding structure that corresponds to the radiation irradiation range has a concave structure portion that is recessed from other portions. 前記凹構造部の奥側には、前記凹構造部の開口部の面積より、大きい面積の断面部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。 The radiation reducing structure according to claim 1, wherein a cross section having an area larger than the area of the opening of the concave structure portion is provided on the inner side of the concave structure portion. 前記外側空間が免震層であ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。 The radiation reducing structure according to claim 1, wherein the outer space is a base isolation layer. 前記外側空間が通路であ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。 The radiation reducing structure according to claim 1 or 2, wherein the outer space is a passage.
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Citations (4)

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

Patent Citations (4)

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