JP4013492B2

JP4013492B2 - Magnetic field shielding device and biomagnetic field measuring device using the same

Info

Publication number: JP4013492B2
Application number: JP2001086628A
Authority: JP
Inventors: 大介鈴木; 篤二ノ宮; 豪宮下; 明彦神鳥; 啓二塚田; 宏一横澤
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2001-03-26
Filing date: 2001-03-26
Publication date: 2007-11-28
Anticipated expiration: 2020-10-30
Also published as: JP2002136494A

Description

【０００１】
【発明の属する技術分野】
本発明は，検査対象から発生する磁場を，高感度な量子干渉素子（ＳＱＵＩＤ:superconducting quantum interference device）からなる複数の磁束計を用いて計測するための磁場遮蔽装置，及び，これを用いる磁場計測方法，磁場計測装置に関する。本発明は，特に，生体の心臓の心筋活動等により発生する生体磁場を計測するための磁場遮蔽装置，及び，これを用いる生体磁場計測方法，生体磁場計測装置に関する。
【０００２】
【従来技術】
径の異なる複数の円筒形シールドを順次同芯状に配置し，各円筒形シールドの間に間隙を形成した磁気シールドが報告されている（従来技術１：特開平９−２１４１６６号公報）。
【０００３】
従来技術１に記載の技術では，厚さ０．１ｍｍ〜０．５ｍｍ，幅２０ｃｍ〜５０ｃｍのテープ状のパーマロイからなる磁気シールド材を用い，軽量なプラスチック円筒を芯として磁気シールド材をスパイラル状に巻きつけ，隙間なく重ね合わせたオーバーラップ部の幅を５ｃｍ〜１０ｃｍとって円筒形に形成されている。オーバーラップ部は，実質的に２層〜５層となり，その厚みの合計が０．５ｍｍ〜３ｍｍ程度となるようなスパイラル状に巻きつけられている。また，オーバーラップ部には，周方向の長さで３０ｃｍ間隔にリベットが設けられ，締め付け固定され，オーバーラップ部の接着面は，金属と金属の接触となっている。
【０００４】
なお，従来技術１には，従来の技術として，Ｎｉ−Ｆｅ系の高透磁率の合金材料であるパーマロイの板を多数枚用いてプレハブ部屋のようなシールドルームを製作するの記載があり，この従来技術には，磁気シールドの製作に長時間を要し，部品点数が多く，磁気シールドが非常に高価になるという問題があり，生体磁気計測機器の価格で磁気シールドの占める割合は大きく，磁気シールドの低価格化が望まれているとの記載がある。
【０００５】
パーマロイの板の代わりに，磁気シールド材として，軟磁性アモルファス合金の膜とポリマーフィルムとを貼り合わせた磁気シールドシートを用いて，軽量なシールドルームを製作することが報告されている（従来技術２：特開平２０００−０７７８９０号公報）。
【０００６】
【発明が解決しようとする課題】
パーマロイの板を組合せてシールドルームを製作する従来技術，従来技術１では，加工後のパーマロイの焼鈍処理を必要とするという問題，広い面積を必要とするという問題，シールドルームの重量が大きくシールドルームを設置する場所に制限があるという問題，シールドルームが高価格となるという問題等があった。従来技術２では，パーマロイの板を組合せてシールドルームを製作する従来技術１よりも，シールドルームの重量が軽量化され，低価格化が実現できるが，広い面積を必要とするという問題は解決されておらず，シールドルームのより軽量化，より低価格化が望まれていた。
【０００７】
本発明の目的は，高透磁率を持つ高透磁率シートを用いて，軽量，小型の高性能な磁場遮蔽装置を低コストで提供し，検査対象，特に，生体から発生する磁場を計測するための磁場計測方法，磁場計測装置を提供することにある。
【０００８】
【課題を解決するための手段】
本発明の代表的な磁場計測装置は，外来磁場の第１の方向に垂直な方向の成分が遮蔽される磁場遮蔽装置と，検査対象から発生する磁場の第１の方向に垂直な方向の成分を検出する複数のＳＱＵＩＤ磁束計を低温に保持するクライオスタット，クライオスタットを保持する装置と，ＳＱＵＩＤ磁束計を駆動し，ＳＱＵＩＤ磁束計からの信号を検出する駆動検出回路と，駆動検出回路の出力を収集し演算処理を行なう演算処理装置と，演算処理装置の出力を表示する表示装置とから構成される。
【０００９】
本発明の磁場遮蔽装置は，中空部をもつ非磁性の複数の筒形部材が第１の方向の軸を同心状に囲み配置され形成される。各筒形部材の面（内面又は／及び外面）に，高透磁率を持つ高透磁率シートの複数枚が，相互に一部分が重複するように貼付して配置される。
【００１０】
最も内側に配置される筒形部材は，第１の方向の一端に第１の開口を，第１の方向の他端に第２の開口を持っている。第１の方向の軸に垂直な方向で複数の筒形部材を貫通する第３の開口が形成されている。最も内側に配置される筒形部材の内側の空間で，外来磁場の第１の方向に垂直な方向の成分が遮蔽される。最も内側に配置される筒形部材の内側の空間に，検査対象が生体である場合には，検査対象部位の体軸方向を第１の方向の軸にほぼ平行にして生体（被験者）を搭載する生体搭載装置（ベッド，椅子）が配置される。
【００１１】
クライオスタットの一部が第３の開口に挿入され，クライオスタットの底面が内側の空間に配置される。第３の開口の直径を，クライオスタットの底面の直径よりも小さくして，クライオスタットの径が小さい部分を第３の開口に挿入する構成により，第３の開口の直径を大きくする必要がないので，外来磁場の磁場遮蔽率を向上させることができる。第３の開口は，検査対象が生体である場合には，生体（被験者）の胸面，又は，背面に対向し，クライオスタットの底面は，生体の胸面，又は，背面に対向して上記内側の空間に配置されている。
【００１２】
クライオスタットの底面と検査対象の表面との位置関係は位置調整装置により調整され，第１の方向に垂直な方向で位置関係が調整される。位置調整装置は，第１の方向に垂直な第２の方向で，クライオスタットの位置，又は検査対象を搭載する搭載装置の位置を変化させることができる。更に，位置調整装置は，第１及び第２の方向に垂直な第３の方向，及び第１の方向で，搭載装置の位置を変化させることができる。
【００１３】
更に，磁場遮蔽装置には，第１の方向の軸に垂直な方向で各筒形部材を貫通する第４の開口が形成されており，検査対象が生体である場合には，第４の開口は被験者の視野内にあり，開放感を被験者に与えている。
【００１４】
【実施の形態】
以下の説明では，検査対象として，代表的な例として生体の心臓を対象として説明する。本発明は，生体の心臓に限定されるものではなく，例えば，一般の検査対象に含まれる磁性体の有無，磁性体の分布の検査にも適用できることは言うまでもない。本発明の装置の構成は大きな面積を必要としないので，例えば，磁性体を含む危険物の検査装置として使用でき，飛行場，港等での手荷物の検査にも適用可能である。
【００１５】
本発明の磁場遮蔽装置では，非晶質又は多結晶質から構成される高透磁率の磁性材料の薄層を含み，柔軟性と薄い厚さを持つ複数の高透磁率シート，あるいは，Ｎｉを含む合金から構成される高透磁率の磁性材料を使用した複数の高透磁率シートが使用される。本発明で使用される高透磁率シートはフレキシブルである。
【００１６】
複数の高透磁率シートは，中空部をもつ非磁性の２個から５個の筒形部材に高透磁率シートの一部分が重複して配置されている。複数の筒形部材は，第１の方向の軸を同心状に囲むように相互に固定され配置される。高透磁率シートには，磁性材料が配置される領域が，非磁性の保持シート（例えば，紙，高分子フィルム，金属フィルム）の間に挟まれて短冊の形状に形成され，複数の短冊は隣接する短冊の長辺で重複し，更に，複数の短冊の長辺がほぼ平行に配列されている。
【００１７】
各高透磁率シートの複数の短冊の短辺は，第１の方向の軸にほぼ平行に配置され，高透磁率シートが複数の各筒形部材の面（内面又は／及び外面）に，各高透磁率シートの複数の短冊の長辺が第１の方向の軸を内側に取り囲むように貼付され，保持されている。このような短冊の形状を持つ磁性材料が配置される複数の領域を配置することにより，外来磁場の磁場遮蔽率を向上させている。
【００１８】
最も内側に配置される筒形部材には，第１の方向の一端に第１の開口が，第１の方向の他端に第２の開口が形成されている。第１の方向の軸に垂直な方向で複数の筒形部材を貫通し，複数のＳＱＵＩＤ磁束計を低温に保持するクライオスタットが挿入される第３の開口が形成されている。最も内側に配置される筒形部材の内側の空間で，外来磁場の第１の方向に垂直な方向の成分が遮蔽される。
【００１９】
複数の筒形部材の第１の方向の軸に垂直な断面のより好ましい形状は，外来磁場の磁場遮蔽率を向上させる観点から，対称性が高い形状がより好ましく円とするが，円を第１の方向の軸に垂直な方向に，例えば，円の直径の約１０％だけ押しつぶした形状でも良い。
【００２０】
最も内側に配置される筒形部材の第１の方向の軸に垂直な断面のより好ましい形状は，直径が約５０ｃｍ以上約２００ｃｍ以下の円であり，最も内側に配置される筒形部材の内部に挿入される被験者に圧迫感を与えないようにする。小児を専用に検査する装置の場合には，もっと間も内側に配置される円筒部材の内径は約５０ｃｍであれば良く，小児，大柄な大人を検査対象とする装置の場合には，もっと間も内側に配置される円筒部材の内径は約５０ｃｍであれば良い。
【００２１】
複数の非磁性の筒形部材として，磁場遮蔽装置の製作，コストの観点から，厚さ０．５ｍｍから１ｍｍをもつ，ＦＲＰの中空円筒，アルミニウムの中空円筒を使用するのがより好ましい。
【００２２】
外来磁場の第１の方向に垂直な方向の成分が遮蔽される，最も内側に配置される筒形部材の内側の空間に，以下に示す３つの何れかの態様で被験者が楽な状態で置かれ，生体磁場を検出しようとする被験者の部位の体軸方向が第１の方向の軸にほぼ平行となるようにして，例えば，被験者の胸部，腹部内の胎児等から発生する生体磁場が検出される。
（１）第１の方向の軸を床面に対してほぼ水平とする場合には，被験者が横たわるベッドが，ほぼ水平の状態で，最も内側に配置される筒形部材の内部に配置される。
（２）第１の方向の軸を床面に対してほぼ垂直とする場合には，被験者は椅子に座っている状態で，最も内側に配置される筒形部材の内部に配置される。
（３）第１の方向の軸を水平面に対して角度が２０度以上３０度以下で傾斜させた場合には，被験者が横たわるベッドを傾斜させた状態で，あるいは，被験者が座っている椅子の背持たれの角度を傾斜させた状態で，最も内側に配置される筒形部材の内部に配置される。
【００２３】
第３の開口及び／又は第４の開口は，以下の３つの何れかの態様で形成される。（１）各筒形部材に穴が開けられており，複数の筒形部材を，第１の方向の軸を同心状に囲むように相互に固定し一体化することにより，各筒形部材の穴により第３の開口が形成される。（１）の態様の他に，各筒形部材の一部分が移動可能に構成され，各筒形部材の一部分の移動により第３及び／又は第４の開口が形成される。
【００２４】
即ち，各筒形部材の一部分が，第１の方向，第１の方向の軸を囲む周方向，第１の方向に交叉する方向の何れかの方向で移動可能であり，各筒形部材の一部分の移動により第３及び／又は第４の開口が形成される。具体的な態様を以下に示す。
（２）各筒形部材が第１の方向で，第１の部分と第２の部分との２つに分割される。第１及び第２の部分の各筒形部材はそれぞれ第１の方向の軸を同心状に囲むように相互に固定し一体化して構成される。第１の部分は第２の部分に対して第１の方向に移動して分離可能である。
【００２５】
第１の部分の各筒形部材は，端部に開口する半円状の部分をもつ第１の切欠き部を持つ。第２の部分の各筒形部材は，端部に開口する半円状の部分をもつ第２の切欠き部を持つ。
【００２６】
第１の部分の第２の部分に対する第１の方向での移動により，第１の部分の端部と第２の部分の端部とが第１の方向で重複する結果，第１及び第２の切欠き部により，第３及び／又は第４の開口が形成される。
【００２７】
第１の部分の第２の部分に対する第１の方向の第１の移動に加え，更に，第１の方向に交叉する方向の第２の移動も可能である。第１の移動，あるいは，第１の移動及び第２の移動により，磁場遮蔽装置に開放部が形成される。
（３）各筒形部材が第１の方向の軸を囲む周方向で，第１の部分と第２の部分との２つに分割される。第１及び第２の部分の各筒形部材はそれぞれ相互に固定し一体化して構成される。第１の部分は第２の部分に対してを囲む周方向に移動可能に構成される。
【００２８】
第１の部分の各筒形部材は，第１の方向にほぼ平行な１辺に開口する半円状の部分をもつ第１の切欠き部を持つ。第２の部分の各筒形部材は，第１の方向にほぼ平行な１辺に開口する半円状の部分をもつ第２の切欠き部を持つ。
【００２９】
第１の部分の第２の部分に対する第１の方向の軸を囲む周方向での移動により，第１の部と第２の部分とが第１の方向の軸を囲む周方向で重複する結果，第１及び第２の切欠き部により，第３の開口が形成される。
【００３０】
第１の部分と第２の部分は，第１の方向にほぼ平行な２辺でそれぞれ，第１の方向の軸を囲む周方向で約１０度から約１５度の範囲で重複する。第１の部分の移動により，第１の方向の軸を囲む周方向で約９０度の範囲の開放部が，磁場遮蔽装置に形成される。
【００３１】
磁場遮蔽装置の他の構成では，上記の（２），（３）で説明したように，各筒形部材が，第１の部分と第２の部分との２つに分割されて形成され，上記の第３の開口を形成するが，上記で説明した第３の開口を形成しない構成とする。クライオスタットの底部は，第１の開口，又第２の開口から挿入される。第４の開口は，被験者の検査対象部位から遠い位置に形成されるので，外来磁場の磁場遮蔽率を劣化させることはない。
【００３２】
以下，本発明に於ける磁場計測の手順について説明する。
【００３３】
まず，磁場遮蔽装置の各筒形部材の一部分を，第１の方向，第１の方向の軸を囲む周方向，第１の方向に交叉する方向の何れかの方向で移動させることにより，開放部を形成する。
【００３４】
第１の方向の軸に交叉する方向から開放部を通して，生体が，磁場遮蔽装置の内側の空間に置かれる生体搭載装置（ベッド，椅子）に搭載される。あるいは，生体が搭載される生体搭載装置が，第１の方向の軸に沿って，第１の方向にほぼ平行な方向，又は，第１の方向の軸に交叉する方向から，開放部を通して磁場遮蔽装置の内側の空間に搬入される。
【００３５】
次に，各筒形部材の一部分を，第１の方向，第１の方向の軸を囲む周方向，第１の方向に交叉する方向の何れかの方向の移動させることにより，開放部を閉鎖する。この結果，第３及び／又は第４の開口部が形成され，第３の開口部に，クライオスタットの一部が挿入された形となる。
【００３６】
磁場遮蔽装置の内側の空間に配置されるクライオスタットの底面と，生体の表面との位置関係を，磁場信号が大きく検出されるように，第１の方向に垂直な方向で調整する。複数のＳＱＵＩＤ磁束計により，生体から発生する磁場の第１の方向に垂直な方向の成分が検出される。
【００３７】
本発明によれば，軽量，小型，低コストで高性能な，外来磁場の高い磁場遮蔽率を持つ磁場遮蔽装置を提供することができ，更に，この磁場遮蔽装置を用いる生体磁場を計測するための磁場計測方法，磁場計測装置を提供できる。
【００３８】
また，本発明の磁場遮蔽装置は，軽量，小型であるため，設置する場所に耐加重性が特に要求されず，小さい面積があれば設置が可能であるので，磁場遮蔽装置，即ち，磁場計測装置を設置する場所に制限がなくなる。
【００３９】
ここで，時間変数をｔ，生体の面を（ｘ，ｙ）面，生体の面に垂直な方向をｚ方向とする。クライオスタットの内部で底面の近傍に等間隔で２次元に格子状に配列されるＳＱＵＩＤ磁束計の位置を（ｘ，ｙ），ＳＱＵＩＤ磁束計により検出される生体磁場の磁場成分（法線成分）をＢｚ（ｘ，ｙ，ｔ）とする。
【００４０】
本発明の磁場計測装置では，生体磁場の接線成分Ｂｘ（ｘ，ｙ，ｔ），Ｂｙ（ｘ，ｙ，ｔ）をそれぞれ，計測された法線成分Ｂｚ（ｘ，ｙ，ｔ）のｘ方向の変化率∂Ｂｚ（ｘ，ｙ，ｔ）／∂ｘ，ｙ方向の変化率∂Ｂｚ（ｘ，ｙ，ｔ）／∂ｙに比例する値として求める。比例定数を１とすると，接線成分Ｂｘ（ｘ，ｙ，ｔ），Ｂｙ（ｘ，ｙ，ｔ）は，（数１），（数２）によって与えられる。
【００４１】
【数１】
Ｂｘ（ｘ，ｙ，ｔ）＝−（∂Ｂｚ（ｘ，ｙ，ｔ）／∂ｘ） …（数１）
【００４２】
【数２】
Ｂｙ（ｘ，ｙ，ｔ）＝−（∂Ｂ（ｘ，ｙ，ｔ）ｚ／∂ｙ） …（数２）
次に，ｘ方向の変化率とｙ方向の変化率の２乗和の平方根に比例する値Ｓｔ（ｘ，ｙ，ｔ）を求める。比例定数を１とすると，磁場波形Ｓｔ（ｘ，ｙ，ｔ）は，（数３）によって与えられる。
【００４３】
【数３】
Ｓｔ（ｘ，ｙ，ｔ）＝√［｛∂Ｂｚ（ｘ，ｙ，ｔ）／∂ｘ｝２＋｛∂Ｂｚ（ｘ，ｙ，ｔ）／∂ｙ｝２］ …（数３）
Ｓｔ（ｘ，ｙ，ｔ）は，生体内部の磁場発生源を（ｘ，ｙ）面に投影した磁場強度情報を与える。ｔとして，Ｑ，Ｒ，Ｓの各波のピーク位置をとり，Ｓｔ（ｘ，ｙ，ｔ）のデータから内挿，外挿により同じ磁場強度を与える（ｘ，ｙ）点を結ぶ等磁場線図を求める。
【００４４】
次に，各点（ｘ，ｙ）について任意の期間での磁場波形Ｓｔ（ｘ，ｙ，ｔ）の積分値Ｉ（ｘ，ｙ）を（数４）により求め，内挿，外挿により積分値Ｉ（ｘ，ｙ）が同じ値の点を結ぶ等積分図を求める。
【００４５】
積分範囲として，例えば，心臓を測定の対象とする時には，Ｑ，Ｒ，Ｓの各波の発生する期間，Ｑ波からＳ波の発生するＱＲＳ波(QRS complex)の期間，Ｔ波の発生する期間等をとる。
【００４６】
【数４】
Ｉ（ｘ，ｙ）＝∫│Ｓｔ（ｘ，ｙ，ｔ）│ｄｔ …（数４）
更に，ｘ，ｙ，ｚの３方向の磁場成分を合成した磁場強度の時間波形Ｖ（ｘ，ｙ，ｔ）を，（数５）により求めることにより，特に，胎児のように動きが激しい場合でも，安定した磁場波形を得ることができる。
【００４７】
【数５】
Ｖ（ｘ，ｙ，ｔ）＝√［｛∂Ｂｚ（ｘ，ｙ，ｔ）／∂ｘ｝２＋｛∂Ｂｚ（ｘ，ｙ，ｔ）／∂ｙ｝２＋｛Ｂｚ（ｘ，ｙ，ｔ）｝２］…（数５）
Ｓｔ（ｘ，ｙ，ｔ）の代わり，Ｖ（ｘ，ｙ，ｔ）を使用して，上記と同様にして，等磁場線図，等積分図を求めることができる。
【００４８】
各ＳＱＵＩＤ磁束計により計測された磁場波形Ｓｔ（ｘ，ｙ，ｔ），Ｖ（ｘ，ｙ，ｔ）を表示すると共に，磁場分布図として，等磁場線図，等積分図を，表示装置の表示画面に表示する。等磁場線図，等積分図を，それらの等高線の高低により色分けをして３次元カラー表示して，診断に有用なデータを得ることができる。
【００４９】
即ち，本発明の磁場計測装置では，接線成分Ｂｘ（ｘ，ｙ，ｔ），Ｂｙ（ｘ，ｙ，ｔ）を計測することなく，法線成分Ｂｚ（ｘ，ｙ，ｔ）の計測のみから，電流源の直上にピークパターンが出現する磁場分布図を得ることができる。この結果，生体内の複数の電流源の位置を直読できるので，心筋梗塞，虚血，不整脈，心筋肥大等の診断，術前術後の心筋状態の変化の評価等の心臓に関する疾患の診断に有用なデータを得ることができる。本発明の磁場計測装置は，特に，成人，胎児の心臓の診断のためのデータ（磁場分布）を，１０秒ないし５分程度の短時間で計測して表示できる。
【００５０】
以下，より具体的に，代表的な実施例を図面を参照して詳細に説明する。
【００５１】
図１は本発明の各実施例で使用される高透磁率を有する高透磁率シート２３の構成例を説明する図である。図２は本発明の各実施例に於ける磁場遮蔽装置を構成する中空円筒への高透磁率シートの配置例を説明する斜視図である。図３は本発明の各実施例に於ける磁場遮蔽装置を構成する中空円筒への高透磁率シートの配置例を説明する断面図である。
【００５２】
フレキシブルな高透磁率シート２３は，短冊の形状の磁性材料（磁性材リボン，磁性材テープ）２５が非磁性の保持シート２６−１，２６−２の間に挟まれて構成される。この高透磁率シート２３は，従来技術２に記載される高透磁率シートと同じである。高透磁率材料として軟磁性アモルファス合金が使用される。
【００５３】
短冊の形状の磁性材リボン２５は，隣接する短冊の長辺で重複して配列され，複数の短冊の長辺はほぼ並行に配列さる。複数の磁性材リボン２５は，保持シート２６−１，２６−２の間に可撓性を有する樹脂，又は接着剤２４により固定されている。保持シート２６−１，２６−２の材質として代表的にＰＥＴ（ポリエチレンテレフタレート）シートが使用される。高透磁率シート２３の大きさは，例えば，縦４５０ｃｍ，横６００ｃｍである。
【００５４】
軟磁性アモルファス合金は，最大比透磁率が５００００以上であるＦｅ−Ｃｕ−Ｎｂ−Ｓｉ−Ｂ系（Ｆｅ：７３．５％，Ｃｕ：１％，Ｎｂ：３％，Ｓｉ：１３．５％，Ｂ：９％）合金であり，結晶粒界の大きさが１００ｎｍ以下の超微結晶組織をもっている。
【００５５】
使用した磁性材リボン２５の厚みは約２０μｍ，保持シート２６−１，２６−２の厚さは３０μｍであり，高透磁率シート２３の全厚は１００μｍである。磁性材リボン２５の厚さを約１０μｍ〜１００μｍ，保持シート２６−１，２６−２の厚さを１０μｍ〜５００μｍとし，高透磁率シート２３の全厚を５０μｍ〜１．５ｍｍとすると，高透磁率シート２３の貼付，折り曲げ作業が容易となる。
【００５６】
本発明の各実施例に於ける磁場遮蔽装置は，同軸に配置される複数の磁場遮蔽円筒６０から構成される。各磁場遮蔽円筒は，内半径の異なる高透磁率シート支持円筒８０と，高透磁率シート支持円筒８０の内周面及び／又は外周面に配置される高透磁率シート層８２から構成される。
【００５７】
各磁場遮蔽円筒には，各実施例に対応して，最も内側に配置される磁場遮蔽円筒の内部にクライオスタットの底面を挿入するための円形の第３の開口４３が形成され，最も内側に配置される磁場遮蔽円筒の内部に配置される患者の視野内に，円形の第４の開口４４が形成され，患者は医師と視線を合わせて対話ができる。
【００５８】
図２には１つの磁場遮蔽円筒６０が示され，高透磁率シート支持円筒８０の外周面に，複数の高透磁率シート２３が接着剤等を用いて貼付されて高透磁率シート層８２が形成されている。高透磁率シート支持円筒８０は，内半径ｒの厚さ０．５ｍｍのアルミニウムの中空円筒を使用している。
【００５９】
高透磁率シート２３の貼付は次ぎの何れかの方法による。（１）複数の高透磁率シート２３が相互に重なり部分を持つように貼付する。（２）下層の高透磁率シート２３の重ね部分を覆うように上層の高透磁率シー２３を貼付する。（３）（１）の方法と（２）の方法とを組合せて貼付する。何れの貼付方法に於いても，高透磁率シート２３の相互の重なりにより，磁性材リボン２５の部分が相互に重なるように，複数の高透磁率シート２３を重ねて貼付する。
【００６０】
各高透磁率シート２３は，各磁性材リボン２５の短辺が高透磁率シート支持円筒８０の中心軸にほぼ平行になるように，各磁性材リボン２５の長辺が保持円筒２１の中心軸を内側に取り囲み，高透磁率シート支持円筒８０の中心軸に垂直な面にほぼ平行になるように，高透磁率シート支持円筒８０に接着剤などを用いて貼付して，高透磁率シート２３の複数層を形成する。
【００６１】
図３は２層の高透磁率シート２３により形成された高透磁率シート層８２を示す。図３では第１層，第２層の各層での高透磁率シート２３の重なりは省略している。
【００６２】
本発明の各実施例に於ける磁場遮蔽装置は，同軸に配置される複数の磁場遮蔽円筒６０のそれぞれを構成する高透磁率シート支持円筒８０は異なる内半径を持つ。隣接する高透磁率シート支持円筒８０の間隔は，１ｃｍから２０ｃｍである。以上説明した磁場遮蔽装置の構成により，外来磁場の複数の磁場遮蔽円筒６０の中心軸に垂直方向の成分を，最も内側の磁場遮蔽円筒の内部で外来磁場を高い磁場遮蔽率で遮蔽する。以下の各実施例では，図面を単純化するために２個の磁場遮蔽円筒を持つ磁場遮蔽装置の構成を例示するが，２個から５個の磁場遮蔽円筒を持つ磁場遮蔽装置の構成としても良い。
【００６３】
以下の各実施例の説明では，同軸に配置される複数の磁場遮蔽円筒６０の中心軸を，簡単のために「磁場遮蔽装置の中心軸」と呼ぶ。更に，以下の各実施例の説明では，複数の磁場遮蔽円筒６０の各円筒が，その中心軸の垂直方向で２個の部分に分割されて構成され，又は，その周方向で２個の部分に分割されて構成され，これら２個の部分を相互に重複させて，複数の磁場遮蔽円筒６０の各円筒が構成される場合にも，重複させて構成され，共軸に配置される複数の磁場遮蔽円筒の中心軸を，同様に，「磁場遮蔽装置の中心軸」と呼ぶ。
（実施例１）
図４は本発明の実施例１の生体磁場計測装置の構成例を示す斜視図である。図５は図４に示す磁場遮蔽装置４０の斜視図である。図６は図４に示す生体磁場計測装置の計測視野の中心を通る面での断面図である。
【００６４】
生体磁場計測装置は，磁場遮蔽装置４０，検査対象（生体）から発生する磁場（生体磁場）を検出する複数のＳＱＵＩＤ磁束計５７を低温に保持するクライオスタット５０と，クライオスタット５０を支持するガントリ３０−２と，磁場遮蔽装置４０及びガントリ３０−２を支持する磁場遮蔽装置・ガントリ支持台３０−１と，クライオスタット５０の内部を冷却するための冷媒供給装置又は冷却装置５５及び冷媒供給線又は冷却伝達線５４，データ収集・センサ制御線５１を介してＳＱＵＩＤ磁束計５７を駆動制御し検出された生体磁場を収集しデータ処理を行なうデータ収集処理・センサ制御装置５２と，データ処理の結果を表示する単数又は複数の表示装置５３から構成される。
【００６５】
クライオスタット５０の内部は，冷媒供給線５４を介して冷媒供給装置５５から供給される液体Ｈｅにより冷却されるか，又は，冷却装置５５として冷凍機を使用してコンプレッサにより冷却伝達線５４を介して冷却されたＨｅガスをクライオスタット５０の内部に配置されるコールドヘッドに供給して冷却される。
【００６６】
磁場遮蔽装置４０は，図２，図３で説明した複数の磁場遮蔽円筒６０から構成され，複数の磁場遮蔽円筒の中心軸（ｙ方向）の正方向に第１の開口４１を，ｙ方向の負方向に第２の開口４２を，中心軸に垂直方向（ｚ方向）の上部にクライオスタット５０を挿入するための，複数の磁場遮蔽円筒を貫通する第３の開口４３を，ベッド２０に横たわる検査対象を観察するための，複数の磁場遮蔽円筒を貫通する第４の開口４４をそれぞれ有する。複数の磁場遮蔽円筒の中心軸（ｙ方向）（磁場遮蔽装置４０の中心軸）は床面に水平である。
【００６７】
磁場遮蔽装置４０は，外来磁場の磁場遮蔽装置４０の中心軸に垂直方向の成分を，最も内側の磁場遮蔽円筒６０−１の内部で，高い磁場遮蔽率で遮蔽する。この結果，ＳＱＵＩＤ磁束計５７は，磁場遮蔽装置２の内部で発生する生体磁場のｚ方向の成分を高感度で検出できる。
【００６８】
ガントリ３０−２の高さはガントリの高さ制御装置３１により制御固定され，検査者（医師）３５は，第４の開口４４からベッド２０に横たわる検査対象（患者）３６の検査部位とクライオスタット５０の底面との位置関係を観察しながら，ガントリの高さ制御ボックス３２を操作する。ガントリの高さ制御ボックス３２からの信号により，ガントリの高さ制御装置３１が制御され，クライオスタット５０の底面のｚ方向の位置が固定される。ｘ方向はｙ方向及びｚ方向に直交する方向に設定される。
【００６９】
クライオスタット１０２の内部の底部近傍にｘｙ面に平行な面（計測面）に配置される複数のＳＱＵＩＤ磁束計５７は，データ収集処理・センサ制御装置５２のＦＬＬ回路によって駆動される。ＦＬＬ回路は，ＳＱＵＩＤ磁束計５７で検出された生体磁場信号を出力する。ＦＬＬ回路の出力は，フィルタリング，増幅され，ＡＤ変換器によってデジタルデータに変換され，データ収集処理・センサ制御装置５２の記憶装置に保存される。データ収集処理・センサ制御装置５２によりデータ処理された結果，例えば，磁場波形Ｓｔ（ｘ，ｙ，ｔ）（（数３）），Ｖ（ｘ，ｙ，ｔ）（（数５））による等磁場線図，等積分図等が，表示装置５３の表示画面に表示される。
【００７０】
検査対象３６が搭載されるベッド２０はｘ及びｙ方向移動装置２１に搭載されており，ｘ及びｙ方向移動装置２１はｘ及びｙ方向移動装置の支持台２２に固定されている。ベッド２０は磁場遮蔽装置４０の最も内側の磁場遮蔽円筒の内部に配置される。
【００７１】
なお，クライオスタット５０の底面の高さを固定された位置として，ｘ及びｙ方向移動装置２１の代りに，ｘ，ｙ，ｚ方向移動装置を使用することもできる。この場合には，ガントリ３０−２と磁場遮蔽装置４０との位置関係が，複数のＳＱＵＩＤ磁束計５７の検出コイルが配列される計測面がもっとも内側の磁場遮蔽円筒６０−１の中心軸にほぼ一致するように，ガントリ３０−２の位置が固定される，又は，ガントリ３０−２と磁場遮蔽装置・ガントリ支持台３０−１とが一体で構成される。勿論，ガントリの高さ制御装置３１，ガントリの高さ制御ボックス３２は不要となる。
【００７２】
検査者（医師）３５は，第４の開口４４からベッド２０の上の検査対象（患者）３６の検査部位とクライオスタット５０の底面との位置関係を観察しながら，ガントリの高さ制御ボックス３２に代えて，ベッド２０のｘ，ｙ，ｚ方向移動制御ボックス（図示せず）を操作する。ｘ，ｙ，ｚ方向移動制御ボックスからの信号により，ベッド２０のｘ，ｙ，ｚ方向移動装置が制御され，ベッド２０のｘ方向，ｙ方向及びｚ方向の位置が固定される。
【００７３】
以上の説明では，検査者（医師）３５が，第４の開口４４を通して患者３６を観察したが，第４の開口４４を設けない構成として，第１の開口４１又は第２の開口４２を通して患者３６を観察しても良いことは言うまでもない。
【００７４】
患者３６の視野内に設けられる第４の開口４４は，患者３６に開放感を与えるとともに，検査者（医師）３５は，第４の開口４４を通して患者３６と近いで対話ができ，正確に患者の状態を観察できる。検査者（医師）３５は，患者３６への指示を容易に伝達できる。患者３６は第４の開口４４を通して磁場遮蔽装置４０の外部を見ることができ，心理的な不安感等を低減する効果がある。
【００７５】
図５に示すように，複数の磁場遮蔽円筒を貫通する第３の開口４３の中心軸と，複数の磁場遮蔽円筒を貫通する第４の開口４４の中心軸とは，約４５度の角度をなしている。図６に示すように，クライオスタット５０の内部の底部には，ＳＱＵＩＤ磁束計５７が２次元に配列され，クライオスタット５０の内部は冷媒５６が満たされている。
【００７６】
磁場遮蔽円筒６０は，第１の磁場遮蔽円筒６０−１，第２の磁場遮蔽円筒６０−２から構成される。第１の磁場遮蔽円筒６０−１と第２の磁場遮蔽円筒６０−２との間には，充填剤７０が充填され，第１の磁場遮蔽円筒６０−１，第２の磁場遮蔽円筒６０−２の形状を安定に保持している。図６に示す例では，充填剤７０を下半分に充填しているが，更に，第３の開口４３，第４の開口４４を除く上半分の部位にも充填しても良い。充填剤７０としては，発泡剤を含む硬質ポリウレタン等が使用できる。発泡剤を含む硬質ポリウレタンは，軽量なので第３の開口４３，第４の開口４４を除く上半分の部位にも充填しても，第１の磁場遮蔽円筒６０−１，第２の磁場遮蔽円筒６０−２の形状を変形させることはない。
（実施例２）
図７は本発明の実施例２の生体磁場計測装置の構成例を示す斜視図である。図８は図７に示す磁場遮蔽装置の斜視図である。図９は図７に示す生体磁場計測装置の計測視野の中心を通る面での断面図であり，一部拡大断面を含む。
【００７７】
以下，実施例１との相違点を中心に説明する。実施例２の生体磁場計測装置の構成では，実施例１で説明した磁場遮蔽装置４０を，ｙ方向で２分割して，磁場遮蔽装置の第１の部分４０−１，磁場遮蔽装置の第２の部分４０−２により構成する。磁場遮蔽装置の第１の部分４０−１は，磁場遮蔽装置の第２の部分４０−２に対して，ｙ方向に移動可能な構成とする。実施例１と同様に，ガントリ３０−２，磁場遮蔽装置の第２の部分４０−２は，磁場遮蔽装置・ガントリ支持台３０−１に支持される。
【００７８】
磁場遮蔽装置の第１の部分４０−１は，磁場遮蔽装置支持台９２に支持固定され，磁場遮蔽装置支持台９２の下部に配置される複数の車輪９１は，床１１７の面に配置されたレール９０−１，９０−２の上に搭載されている。磁場遮蔽装置の第１の部分４０−１は，レール９０−１，９０−２の上でｙ方向に移動できる。この移動により磁場遮蔽装置の第１の部分４０−１と磁場遮蔽装置の第２の部分４０−２とを分離できる。
【００７９】
この結果，開放された空間で，医師３５は楽な姿勢で患者３６をベッド２０に搭載でき，又は，患者３６は楽にベッド２０横たわることができる。患者は，足部が先にクライオスタットの下部を通過し，最終的に胸部がクライオスタットの下部に到達するように搭載される。医師３５は，患者３６の検査部位とクライオスタット５０の底面との位置関係を，効率良く調整できる。調整後，分離された磁場遮蔽装置の第１の部分４０−１を移動させて，磁場遮蔽装置の第１の部分４０−１と磁場遮蔽装置の第２の部分４０−２とをｙ方向で重複させて，第３の開口４３，第４の開口４４を形成できる。
【００８０】
この結果，外来磁場の磁場遮蔽装置４０の中心軸に垂直方向の成分を，最も内側の磁場遮蔽円筒４０−１−１，４０−２−１の内部で，高い磁場遮蔽率で遮蔽できる。高い磁場遮蔽率で外来磁場が遮蔽された空間で，検査部位からの生体磁場のｚ方向の成分を高感度で検出できる。
【００８１】
図８に示すように，磁場遮蔽装置の第１の部分４０−１を構成する磁場遮蔽円筒，磁場遮蔽装置の第２の部分４０−２を構成する磁場遮蔽円筒はそれぞれ，重複させた時に第３の開口４３，第４の開口４４を形成するように，円周の一部をもつ切欠き部分を持っている。
【００８２】
図９に示すように，磁場遮蔽装置４０は，磁場遮蔽装置の第１の部分４０−１，磁場遮蔽装置の第２の部分４０−２とから構成される。磁場遮蔽装置の第１の部分４０−１は，第１の磁場遮蔽内側円筒４０−１−１，第１の磁場遮蔽外側円筒４０−１−２とから構成される。磁場遮蔽装置の第２の部分４０−２は，第２の磁場遮蔽内側円筒４０−２−１，第２の磁場遮蔽外側円筒４０−２−２とから構成される。
【００８３】
第２の磁場遮蔽外側円筒４０−２−２の内側に，第１の磁場遮蔽外側円筒４０−１−２が重複して配置され，第２の磁場遮蔽内側円筒４０−２−１の内側に，第１の磁場遮蔽内側円筒４０−１−１が重複して配置される。図９にはこの重複部分に第３の開口が示されている。
【００８４】
拡大断面に示すように，第２の磁場遮蔽内側円筒４０−２−１，第２の磁場遮蔽外側円筒４０−２−２の各高透磁率シート支持円筒８０の内側に，高透磁率シート２３により高透磁率シート層８２が形成されている。第１の磁場遮蔽内側円筒４０−１−１，第１の磁場遮蔽外側円筒４０−１−２の各高透磁率シート支持円筒８０の外側に，高透磁率シート２３により高透磁率シート層８２が形成されている。この結果，重複部分で，高透磁率シート層８２を近接させる構成として，漏れ磁束を減少させて磁場遮蔽効果を高めている。
【００８５】
また，磁場遮蔽装置４０の中心軸に平行な方向で第３の開口の外側に於ける，第２の磁場遮蔽外側円筒４０−２−２と第１の磁場遮蔽外側円筒４０−１−２とが重複する距離，第２の磁場遮蔽内側円筒４０−２−１と第１の磁場遮蔽内側円筒４０−１−１とが重複する距離は，第３の開口の直径の約１／２から約１／４とする。重複部分を充分大きくして磁場遮蔽効果を高めている。
【００８６】
ベッド２０，ｘ及びｙ方向移動装置２１を搭載するベッド及び移動装置の支持台２２は，スペーサ１４０−１を介して第２の磁場遮蔽内側円筒４０−２−１の内部に配置される。実施例１と同様の目的で，第２の磁場遮蔽内側円筒４０−２−１と第２の磁場遮蔽外側円筒４０−２−２との間の下半分に，充填剤７０−１が充填され，第１の磁場遮蔽内側円筒４０−１−１と第１の磁場遮蔽外側円筒４０−１−２間の下半分に，充填剤７０−２が充填されている。図９示す例では，充填剤７０−１，７０−２を下半分に充填しているが，更に，第３の開口４３，第４の開口４４を除く上半分の部位にも充填しても良いことは言うまでもない。
【００８７】
なお，実施例１と同様に，クライオスタット５０の底面の高さを固定された位置として，ｘ及びｙ方向移動装置２１の代りに，ベッド２０のｘ，ｙ，ｚ方向移動装置を使用できるとは言うまでもない。更に，実施例１と同様に，第４の開口がない構成としても良いことは言うまでもない。
（実施例３）
図１０は本発明の実施例３の生体磁場計測装置の構成例を示す斜視図である。図１１は図１０に示す磁場遮蔽装置の斜視図であり，一部拡大断面を含む。図１２は図７に示す生体磁場計測装置への検査対象（患者）の出し入れを説明する断面図であり，一部拡大断面を含む。
【００８８】
以下，実施例１との相違点を中心に説明する。実施例１で説明した磁場遮蔽装置４０を，周方向で２分割して，磁場遮蔽装置の第１の部分４０−３，磁場遮蔽装置の第２の部分４０−４により構成する。磁場遮蔽装置の第１の部分４０−３は，磁場遮蔽装置の第２の部分４０−４に対して，周方向に移動可能な構成とする。実施例１と同様に，ガントリ３０−２，磁場遮蔽装置の第２の部分４０−４は，磁場遮蔽装置・ガントリ支持台３０−１に支持される。
【００８９】
図１１，図１２に示すように，磁場遮蔽装置の第１の部分４０−３は，ｙ方向の正方向及び負方向の端部で結合板１５０−１により結合された，第１の磁場遮蔽内側円筒４０−３−１，第２の磁場遮蔽外側円筒４０−３−２から構成される。同様に，磁場遮蔽装置の磁場遮蔽装置の第２の部分４０−４は，ｙ方向の正方向及び負方向の端部で結合板１５０−２（図示せず）により結合された，第２の磁場遮蔽内側円筒４０−４−１，第２の磁場遮蔽外側円筒４０−４−２から構成される。図１０，図１１，図１２に示すように，第１の磁場遮蔽内側円筒４０−３−１，第２の磁場遮蔽外側円筒４０−３−２を貫通する第４の開口４０が形成されている。
【００９０】
第４の開口４０の第１の磁場遮蔽内側円筒４０−３−１の内側，及び，第２の磁場遮蔽外側円筒４０−３−２の外側はそれぞれ，透明な曲面板でカバーがされており，磁場遮蔽装置の第１の部分４０−３の，磁場遮蔽装置の第２の部分４０−４に対する周方向の移動の時，手，着衣等を挟み込まないようにしている。
【００９１】
磁場遮蔽装置の第１の部分４０−３は約１１０度の円周部を持ち，磁場遮蔽装置の第２の部分４０−４は約２７０度の円周部を持ち，相互に両端部でそれぞれ約１０度の範囲で重複する構成とする。即ち，第１の磁場遮蔽内側円筒４０−３−１と第２の磁場遮蔽内側円筒４０−４−１，及び，第２の磁場遮蔽外側円筒４０−３−２と第２の磁場遮蔽外側円筒４０−４−２はそれぞれ，磁場遮蔽装置の中心軸に平行な両端部で約１０度の範囲で重複する時，閉じた状態の磁場遮蔽装置を形成し，約１１０度の範囲で重複する時，開口部を有し，開放された状態の磁場遮蔽装置を形成する。閉じた状態で重複部分を充分大きくして磁場遮蔽効果を高めている。
【００９２】
第２の磁場遮蔽外側円筒４０−３−２の高透磁率シート支持円筒８０の外面の周面には，拡大断面に示すようにＴの字型の細長い板がガイド１０５−２として配置されており，第２の磁場遮蔽外側円筒４０−４−２の高透磁率シート支持円筒８０の内面の周面にガイド１０５−２を受け入れるＴの字型の細長い溝が形成されている。
【００９３】
同様に，第１の磁場遮蔽内側円筒４０−３−１の高透磁率シート支持円筒の外面の周面には，Ｔの字型の細長い板がガイド１０５−１として配置されており，第２の磁場遮蔽内側円筒４０−４−１の高透磁率シート支持円筒の内面の周面にガイド１０５−１を受け入れるＴの字型の細長い溝（図示せず）が形成されている。
【００９４】
なお，高透磁率シート２３により高透磁率シート層８２は，第２の磁場遮蔽内側円筒４０−４−１，第２の磁場遮蔽外側円筒４０−４−２の各高透磁率シート支持円筒の外面に，第１の磁場遮蔽内側円筒４０−３−１，第２の磁場遮蔽外側円筒４０−３−２の各高透磁率シート支持円筒の内面に，それぞれ形成されている。
【００９５】
図１１に示すように，磁場遮蔽装置の第１の部分４０−３を構成する磁場遮蔽円筒，磁場遮蔽装置の第２の部分４０−４を構成する磁場遮蔽円筒はそれぞれ，重複させた時に第３の開口４３を形成するように，円周の一部をもつ切欠き部分を持っている。
【００９６】
図１２（ａ）は，ベッド２０に患者３６が横たわり，検査部位からの生体磁場が計測される時の状態を示す。磁場遮蔽装置の第１の部分４０−３を構成する磁場遮蔽円筒，磁場遮蔽装置の第２の部分４０−４を構成する磁場遮蔽円筒はそれぞれ重複している。第１の部分４０−３と第２の部分４０−４の位置関係はロックにより固定されている。この状態で，外来磁場の磁場遮蔽装置４０の中心軸に垂直方向の成分を，最も内側の磁場遮蔽円筒４０−３−１，４０−４−１の内部で，高い磁場遮蔽率で遮蔽できる。高い磁場遮蔽率で外来磁場が遮蔽された空間で，検査部位からの生体磁場のｚ方向の成分を高感度で検出できる。
【００９７】
図１２（ｂ）は，磁場遮蔽装置の第１の部分４０−３が，第１の部分４０−３に取り付けた取っ手（図示せず）を用いて手動で，又は自動で，周方向に移動され，第１の部分４０−３の位置がロックされ，開口部が形成され，約９０度の角度範囲で開放空間が形成された状態を示す。この結果，開放空間で，医師３５は楽な姿勢で，ベッド移動台１０３から患者３６をベッド２０に搭載でき，もしくは，患者３６は楽にベッド２０横たわることができ，医師３５は，患者３６の検査部位とクライオスタット５０の底面との位置関係を，効率良く調整できる。
【００９８】
なお，実施例１と同様に，クライオスタット５０の底面の高さを固定された位置として，ｘ及びｙ方向移動装置２１の代りに，ベッド２０のｘ，ｙ，ｚ方向移動装置を使用できるとは言うまでもない。更に，実施例１と同様に，第４の開口がない構成としても良いことは言うまでもない。
（実施例４）
本発明の実施例４の生体磁場計測装置は，実施例３の生体磁場計測装置の構成の一部を変更した，病室のベッドの近傍まで移動可能な構成としたベッドサイド用生体磁場計測装置である。
【００９９】
磁場遮蔽装置・ガントリ支持台３０−１には，移動可能なように複数個の車輪１００が配置されており，また，ベッド及び移動装置の支持台２２にも移動可能なように複数個の車輪２９−１，２９−２，２９−３，２９−４（図示せず）が配置されている。複数個の１００−１を持つ台車に，データ収集処理・センサ制御装置５２，表示装置５３，冷媒供給装置又は冷却装置５５が搭載される。
【０１００】
実施例４のベッドサイド用生体磁場計測装置では，クライオスタット５０の底面の高さを固定された位置として，ｘ及びｙ方向移動装置２１の代りに，ベッド２０のｘ，ｙ，ｚ方向移動装置２１’を使用する。
【０１０１】
図１２（ｃ）に示すように，車輪２９’−１，２９’−２，２９’−３（図示せず），２９’−４（図示せず）を持ち，搭載するベッド移動台１０３の近傍に，ベッドサイド用生体磁場計測装置を移動させた後，図１２（ｂ）に示すように，磁場遮蔽装置の第１の部分４０−３が周方向に移動されその位置がロックされ，約９０度の角度範囲で，開放空間が形成された状態とする。
【０１０２】
ベッドサイド用生体磁場計測装置のベッド２０のｘ，ｙ，ｚ方向移動装置２１’と，ベッド移動台１０のベッド２０−１，ｘ，ｙ，ｚ方向移動装置２１’とを使用して，ｘ，ｙ，ｚ方向の各方向での，ベッド２０及びベッド２０−１の位置を調整して，容易に患者３６をベッド２０−１からベッド２０に移動させることができる。
【０１０３】
ベッド２０−１，ｘ，ｙ，ｚ方向移動装置２１’を使用して，医師３５は，患者３６の検査部位とクライオスタット５０の底面との位置関係を調整する。その後，図１２（ａ）に示す状態で，患者３６の検査部位からの生体磁場が計測される。生体磁場の計測終了後，図１２（ｂ）に示す状態として，ベッド２０のｘ，ｙ，ｚ方向移動装置２１’と，ベッド移動台１０のベッド２０−１，ｘ，ｙ，ｚ方向移動装置２１’とを使用して，ｘ，ｙ，ｚ方向の各方向での，ベッド２０及びベッド２０−１の位置を調整して，容易に患者３６をベッド２０からベッド２０−１に移動させることができる。
【０１０４】
実施例４のベッドサイド用生体磁場計測装置は，自由に移動でき，病院内を移動して入院患者のベッドサイドでの検査が可能となる。従って，救急患者，ベッドに寝たきりの患者を測定する際，患者は，生体磁場計測装置が設置された検査室へ移動する必要がなく，患者の負担が軽減される。
（実施例５）
図１３は本発明の実施例５の実施例であり，実施例３又は実施例４で説明した生体磁場計測装置を自動車に搭載した検診車（移動式生体磁場計測装置）の例を示す一部破断部を含む斜視図である。生体磁場計測装置の全体が，車内の床１１０に置かれた除振台１１１の上に配置固定され，外部の振動を遮断している。自動車は，固定用のアンカー１１２を備えており，生体磁場の計測の時にはアンカー１１２を地面に下ろして自動車を地面に固定する。この検診車は，学校，保健所等の地域コミュニティーへ移動して定期的な集団検診等に利用される。
（実施例６）
図１４は本発明の実施例６の生体磁場計測装置に使用される磁場遮蔽装置の構成例を示す斜視図であり，一部拡大を含む。図１５は，図１４に示す磁場遮蔽装置を使用する生体磁場計測装置の計測視野の中心を通る面での断面図である。
【０１０５】
図１４に示す磁場遮蔽装置は，実施例１で説明した磁場遮蔽装置４０を周方向で２分割して，磁場遮蔽装置の第１の部分４０−５，磁場遮蔽装置の第２の部分４０−６により構成する。磁場遮蔽装置の第１の部分４０−５は，磁場遮蔽装置の第２の部分４０−６に対して周方向に移動可能な構成とする。
【０１０６】
第２の磁場遮蔽内側円筒４０−６−１，第２の磁場遮蔽外側円筒４０−６−２の下部には複数の車輪１１８が固定されており，図１４の拡大断面の示すように，車輪１１８は，床１１７に形成された移動ガイド溝１１９の内部に配置されている。第２の磁場遮蔽内側円筒４０−６−１，第２の磁場遮蔽外側円筒４０−６−２の上部は結合板１１５により結合されている。結合板１１５にには，天井に配置される円形のガイドレールに連結させるための移動のための上部結合部１１６が固定されている。
【０１０７】
図１４の拡大断面に示すように，第２の磁場遮蔽内側円筒４０−６−１，第２の磁場遮蔽外側円筒４０−６−２の各高透磁率シート支持円筒８０の内側に，高透磁率シート２３により高透磁率シート層８２が形成されている。第１の磁場遮蔽内側円筒４０−５−１，第１の磁場遮蔽外側円筒４０−５−２の各高透磁率シート支持円筒８０の外側に，高透磁率シート２３により高透磁率シート層８２が形成されている。この結果，重複部分で，高透磁率シート層８２を近接させる構成として，漏れ磁束を減少させて磁場遮蔽効果を高めている。
【０１０８】
図１５に示すように，第１の磁場遮蔽内側円筒４０−５−１は磁場遮蔽円筒支持体１２８により，第２の磁場遮蔽外側円筒４０−５−２は磁場遮蔽円筒支持体１２０により，それぞれ床１１７に固定される。ＳＱＵＩＤ磁束計５７が２次元に配列される側のクライオスタット５０−１は，ガントリ１２４に移動可能に固定される。ｘ，ｙ方向にそれぞに移動可能な椅子１２２に座った患者３６の検査部位と，ＳＱＵＩＤ磁束計５７が配列される側のクライオスタット５０−１の面との位置関係，クライオスタット５０−１の高さ位置が調整された後に，クライオスタット５０−１は，クライオスタット位置固定ロック１２６により固定される。
【０１０９】
磁場遮蔽装置の第２の部分４０−６の高さは，磁場遮蔽装置の第１の部分４０−５の高さよりも高くして，磁場遮蔽装置の第２の部分４０−６を回転させるための構造を単純にする。磁場遮蔽装置の第２の部分４０−６は約２００度の円周部を持ち，磁場遮蔽装置の第１の部分４０−５は１８０度の円周部を持ち，相互に両端部でそれぞれ約１０度の範囲で重複する構成とする。即ち，第１の磁場遮蔽内側円筒４０−５−１と第２の磁場遮蔽内側円筒４０−６−１，及び，第２の磁場遮蔽外側円筒４０−５−２と第２の磁場遮蔽外側円筒４０−６−２はそれぞれ，磁場遮蔽装置の中心軸に平行な両端部で約１０度の範囲で重複する時，閉じた状態の磁場遮蔽装置を形成し，約１８０度の範囲で重複する時，開放された状態の磁場遮蔽装置を形成する。
【０１１０】
閉じた状態で重複部分を充分大きくして磁場遮蔽効果を高めて，外来磁場の磁場遮蔽装置４０の中心軸に垂直方向の成分を，最も内側の磁場遮蔽円筒４０−５−１，４０−６−１の内部で，高い磁場遮蔽率で遮蔽できる。高い磁場遮蔽率で外来磁場が遮蔽された空間で，検査部位からの生体磁場のｘ方向の成分を高感度で検出できる。
【０１１１】
磁場遮蔽装置の第２の部分４０−６を回転させて開放空間を作り，患者３６が椅子１２２に座った状態で，医師は，患者３６の検査部位とクライオスタット５０−１の外面との位置関係を調整する。
【０１１２】
実施例６で使用する磁場遮蔽装置を構成する各磁場遮蔽円筒６０の中心軸は共軸に配置され，各磁場遮蔽円筒は中心軸に対して平行な面で分割されている。各磁場遮蔽円筒は垂直に配置される。実施例６で使用する磁場遮蔽装置では，患者３６は，容易に磁場遮蔽装置の内部に入ることができ，検査部位の位置合わせ効率よくできる。実施例６で使用する磁場遮蔽装置は小型であり，生体磁場計測装置の設置面積が小さくてすむ。
【０１１３】
なお，クライオスタット５０−１の高さを固定された位置として，ｘ及びｙ方向移動装置の代りに，検査対象３６が座る椅子１２２のｘ，ｙ，ｚ方向移動を制御するｘ，ｙ，ｚ方向移動装置を使用して，ＳＱＵＩＤ磁束計５７が配列される側のクライオスタット５０−１の面と検査対象３６の検査部位の面との位置合わせを行なうことができるとは言うまでもない。
（実施例７）
図１６は本発明の実施例７であり，図１４，図１５に示す磁場遮蔽装置を使用する生体磁場計測装置の計測視野の中心を通る面での断面図である。実施例７の生体磁場計測装置では，図１４，図１５に示す磁場遮蔽装置を，床１１７に対して２０度以上３０度以下で傾斜している床１１７−１に配置する。その他の構成は，実施例６と同じである。
（実施例８）
図１７は本発明の実施例８の生体磁場計測装置の構成例を示す斜視図である。図１８は図１７に示す生体磁場計測装置の計測視野の中心を通る面での断面図である。
【０１１４】
以下，実施例１との相違点を中心に説明する。磁場遮蔽装置４０−７は，磁場遮蔽内側円筒４０−７−１，磁場遮蔽外側円筒４０−７−２から構成され，磁場遮蔽装置４０−７は，床１１７に固定される磁場遮蔽装置支持体１３０により保持されている。
【０１１５】
実施例８では，磁場を検出する検出コイルが薄膜で掲載される平面型のＳＱＵＩＤ磁束計を使用するので小型のクライオスタットを使用できる。実施例８では，実施例１で説明した磁場遮蔽装置４０の構成で，クライオスタット５０を挿入する第３の開口４３を形成せず，ＳＱＵＩＤ磁束計が底部に２次元に配置されるクライオスタット５０−２を磁場遮蔽内側円筒４０−７−１の内部に配置する。クライオスタット５０−２は，クライオスタット保持板１３２により保持され，クライオスタット保持板１３２は，床１１７に固定されるクライオスタット保持板の固定台１３１に保持される。
【０１１６】
ベッド２０，ｘ及びｙ方向移動装置２１を搭載するベッド及び移動装置の支持台２２は，スペーサ１４０−２を介して磁場遮蔽内側円筒４０−７−１の内部に配置される。図１８示す例では，充填剤７０−３を下半分に充填しているが，更に，上半分の部位にも充填しても良いことは言うまでもない。
【０１１７】
実施例８では，実施例１で説明した第３の開口を形成しないので，外来磁場の磁場遮蔽装置４０の中心軸に垂直方向の成分を，最も内側の磁場遮蔽円筒４０−７−１の内部で，実施例１に示す磁場遮蔽装置よりも高い磁場遮蔽率で遮蔽できる。より高い磁場遮蔽率で外来磁場が遮蔽された空間で，検査部位からの生体磁場のｚ方向の成分を高感度で検出できる。
【０１１８】
ベッド２０に載せられた患者は，第２の開口４２から磁場遮蔽内側円筒４０−７−１の内部に，より好ましくは，足部が先にクライオスタット５０−２の下部を通過するようにし，その後，胸部がクライオスタットの下部に到達するようにして，圧迫感をできるだけ少なくするようにして，挿入される。勿論，図１８に示すように，頭部から先に，磁場遮蔽内側円筒４０−７−１の内部に搬入しても良い。医師は，患者３６の検査部位とクライオスタット５０−２の底面との位置関係を，ベッド２０のｘ及びｙ方向移動装置２１と，クライオスタット保持板の固定台１３１に組み込まれた高さ方向移動装置（位置調整装置）とを使用して調整した後に，検査部位からの生体磁場を計測する。
【０１１９】
実施例１と同様にして，クライオスタット５０−２の高さを固定された位置として，ｘ及びｙ方向移動装置２１の代りに，ベッド２０のｘ，ｙ，ｚ方向移動装置を使用できるとは言うまでもない。更に，実施例１と同様に，第４の開口がない構成としても良いことは言うまでもない。
（実施例９）
図１９は本発明の実施例１に示す生体磁場計測装置によって計測された磁場波形の例を示す図である。図１９はクライオスタットの内部の底部で正方形の各頂点に配置された合計４チャンネルのＳＱＵＩＤ磁束計を用いて検出した健常者の心臓から発生する磁場を示し，１チャンネルの磁場波形を示す。図１９の横軸は時間（ｓｅｃ），縦軸は検出された磁場の微分値（ｐＴ／ｍ）を示す。
【０１２０】
実施例８の計測結果を得る時に使用した磁場遮蔽装置４０の構成は以下の通りである。使用した磁場遮蔽装置は，内側から外側に向け，共軸に配置された第１，第２，第３の磁場遮蔽円筒６０から構成され，高透磁率シート支持円筒８０の外側に，高透磁率シート２３により高透磁率シート層８２を形成した。使用した磁場遮蔽装置では，第４の開口は設けていない。第３の開口は，４チャンネルのＳＱＵＩＤ磁束計が配置される断面が円形のクライオスタットを挿入するため，半径３０ｃｍの円形とした。
【０１２１】
第１の磁場遮蔽円筒，第２の磁場遮蔽円筒，第３の磁場遮蔽円筒としてそれぞれ内半径８０ｃｍ，９０ｃｍ，１００ｃｍを持ち，厚さ０．５ｍｍ，長さ２００ｃｍのアルミニウムの中空円筒を使用した。第３の開口は，各中空円筒の長さ方向の中心部に設けた。
【０１２２】
使用した高透磁率シート２３は市販品（日立金属株式会社，商品名ファインメット）を使用した。この高透磁率シート２３は，高透磁率材料として，結晶粒界の大きさが１００ｎｍ以下の超微結晶組織をもち，最大比透磁率が５００００以上のＦｅ−Ｃｕ−Ｎｂ−Ｓｉ−Ｂ系（Ｆｅ：７３．５％，Ｃｕ：１％，Ｎｂ：３％，Ｓｉ：１３．５％，Ｂ：９％）の軟磁性アモルファス合金を使用している。
【０１２３】
使用した高透磁率シートの構成は，磁性材リボン（高透磁率材料）２５の厚み約２０μｍ，保持シート２６−１，２６−２の厚さ３０μｍ，高透磁率シート２３の全厚１００μｍである。面積６１０ｃｍ×２４０ｃｍの高透磁率シート２３を重複させて各アルミニウムの中空円筒の外周面に貼付し，厚さ約１ｍｍの高透磁率シート層８２を形成した。
【０１２４】
フレキシブルな高透磁率シート２３は，図２に示すように，磁性材リボン２５の短辺が各中空円筒の中心軸にほぼ平行になるように，各磁性材リボン２５の長辺が各中空円筒の中心軸を内側に取り囲み，各中空円筒の中心軸に垂直な面にほぼ平行になるように，各中空円筒の周面に接着剤を用いて貼付して高透磁率シート２３の複数層を形成した。
【０１２５】
簡単な構成の磁場遮蔽装置を使用することにより，外来磁場の磁場遮蔽装置の中心軸（第１，第２，第３の磁場遮蔽円筒の中心軸）に垂直方向の成分を，最も内側の第１の磁場遮蔽円筒の中心軸の位置で，−３５ｄＢに減衰することができた。即ち，最も内側の第１の磁場遮蔽円筒の中心軸の位置で，外来磁場の，磁場遮蔽装置の中心軸の垂直方向の成分を，−３５ｄＢに減衰させることができる。この結果，ＳＱＵＩＤ磁束計は，磁場遮蔽装置の内部に置かれた生体の検査部位から発生する生体磁場のｚ方向の成分を高感度で検出できる。
【０１２６】
使用した磁場遮蔽装置の磁場遮蔽率は，磁場遮蔽装置の中心軸の位置で１／５６であり，成人健常者の心臓から発生する磁場をＲ波の出現時点でＳＮ比１０以上で計測できることが判明した。
【０１２７】
なお，磁性材リボン２５の長辺が各中空円筒の中心軸に平行となるように，高透磁率シート２３を各中空円筒の周面に貼付して高透磁率シート２３の複数層を形成して各磁場遮蔽円筒を形成した場合には，外来磁場の，磁場遮蔽装置の中心軸に垂直方向の成分を，最も内側の第１の磁場遮蔽円筒の中心軸の位置で，約−３１ｄＢに減衰できた。
【０１２８】
以上説明した，実施例１，実施例２，実施例３，実施例４，実施例５，実施例８の構成に於いて，第４の開口を設ける場合，最も内側の磁場遮蔽円筒の内直径が約１ｍの時，第４の開口の直径は約３０ｃｍとすることができる。
【０１２９】
また，実施例１，実施例２，実施例８の構成に於いて，磁場遮蔽装置の最も内側の磁場遮蔽円筒の内部空間への検査対象（患者）の搬入は，足部が先にクライオスタットの下部を通過するようにし，最終的に胸部がクライオスタットの下部に到達するようにして，圧迫感をできるだけ少なくするように行なう。
【０１３０】
【発明の効果】
本発明によれば，高透磁率を持つ高透磁率シートを用いて，軽量，小型，低コストで高性能な高い磁場遮蔽率を持つ磁場遮蔽装置を実現できる。本発明の磁場遮蔽装置は軽量，小型であるため，設置する場所に耐加重性が特に要求されず，小さい面積があれば設置が可能であり，磁場遮蔽装置，即ち，磁場計測装置を設置する場所に制限がなくなる。
【０１３１】
本発明の磁場計測装置では，磁場の２方向の接線成分を計測することなく，磁場の法線成分の計測のみから，電流源の直上にピークパターンが出現する磁場分布図を得ることができる。この結果，検査対象，特に，生体内の複数の電流源の位置を直読できるので，検査対象を生体とする場合，成人，胎児の心臓に関する疾患の診断に有用なデータを得ることができる。本発明の磁場計測装置は，短時間で検査対象からの磁場を計測して表示できる。
【図面の簡単な説明】
【図１】本発明の各実施例で使用される高透磁率を有する高透磁率シートの構成例を説明する図。
【図２】本発明の各実施例に於ける磁場遮蔽装置を構成する中空円筒への高透磁率シートの配置例を説明する斜視図。
【図３】本発明の各実施例に於ける磁場遮蔽装置を構成する中空円筒への高透磁率シートの配置例を説明する断面図。
【図４】本発明の実施例１の生体磁場計測装置の構成例を示す斜視図。
【図５】図４に示す磁場遮蔽装置の斜視図。
【図６】図４に示す生体磁場計測装置の計測視野の中心を通る面での断面図。
【図７】本発明の実施例２の生体磁場計測装置の構成例を示す斜視図。
【図８】図７に示す磁場遮蔽装置の斜視図。
【図９】図７に示す生体磁場計測装置の計測視野の中心を通る面での断面図。
【図１０】本発明の実施例３の生体磁場計測装置の構成例を示す斜視図。
【図１１】図１０に示す磁場遮蔽装置の斜視図。
【図１２】図７に示す生体磁場計測装置への検査対象（患者）の出し入れを説明する断面図。
【図１３】本発明の実施例５の実施例であり，実施例３又は実施例４の生体磁場計測装置を自動車に搭載した検診車の例を示す一部破断部を含む斜視図。
【図１４】本発明の実施例６の生体磁場計測装置に使用される磁場遮蔽装置の構成例を示す斜視図。
【図１５】図１４に示す磁場遮蔽装置を使用する生体磁場計測装置の計測視野の中心を通る面での断面図。
【図１６】本発明の実施例７であり，図１４に示す磁場遮蔽装置を使用する生体磁場計測装置の計測視野の中心を通る面での断面図。
【図１７】本発明の実施例８の生体磁場計測装置の構成例を示す斜視図。
【図１８】図１７に示す生体磁場計測装置の計測視野の中心を通る面での断面図。
【図１９】本発明の実施例１の生体磁場計測装置によって計測された磁場波形の例を示す図。
【符号の説明】
２０，２０−１…ベッド，２１…ｘ及びｙ方向移動装置，又はｘ，ｙ，ｚ方向移動装置，２１’…ｘ，ｙ，ｚ方向移動装置，２２…ベッド及び移動装置の支持台，２３…高透磁率シート，２４…可撓性の樹脂又は接着剤，２５…磁性材リボン，２６−１，２６−２…保持シート，２９−１，２９−２，２９−３，２９−４…車輪，２９’−１，２９’−２，２９’−３，２９’−４…車輪，３０−１…磁場遮蔽装置・ガントリ支持台，３０−２…ガントリ，３１…ガントリの高さ制御装置，３２…ガントリの高さ制御ボックス，３５…検査者（医師），３６…検査対象（患者），４０…磁場遮蔽装置，４０−１…磁場遮蔽装置の第１の部分，４０−１−１…第１の磁場遮蔽内側円筒，４０−１−２…第１の磁場遮蔽外側円筒，４０−２…磁場遮蔽装置の第２の部分，４０−２−１…第２の磁場遮蔽内側円筒，４０−２−２…第２の磁場遮蔽外側円筒，４０−３…磁場遮蔽装置の第１の部分，４０−３−１…第１の磁場遮蔽内側円筒，４０−３−２…第２の磁場遮蔽外側円筒，４０−４…磁場遮蔽装置の第２の部分，４０−４−１…第２の磁場遮蔽内側円筒，４０−４−２…第２の磁場遮蔽外側円筒，４０−５…磁場遮蔽装置の第１の部分，４０−５−１…第１の磁場遮蔽内側円筒，４０−５−２…第２の磁場遮蔽外側円筒，４０−６…磁場遮蔽装置の第２の部分，４０−６−１…第２の磁場遮蔽内側円筒，４０−６−２…第２の磁場遮蔽外側円筒，４０−７…磁場遮蔽装置，４０−７−１…磁場遮蔽内側円筒，４０−７−２…磁場遮蔽外側円筒，４１…第１の開口，４２…第２の開口，４３…第３の開口，４４…第４の開口，５０，５０−１，５０−２…クライオスタット，５１…データ収集・センサ制御線，５２…データ収集処理・センサ制御装置，５３…表示装置，５４…冷媒供給線又は冷却伝達線，５５…冷媒供給装置又は冷却装置，５６…冷媒，５７…ＳＱＵＩＤ磁束計，６０…磁場遮蔽円筒，６０−１…第１の磁場遮蔽円筒，６０−２…第２の磁場遮蔽円筒，７０，７０−１，７０−２，７０−３…充填剤，８０…高透磁率シート支持円筒，８２…高透磁率シート層，９０−１，９０−２…レール，９１…車輪，９２…磁場遮蔽装置支持台，１００，１００−１…車輪，１０１…結合部，１０３…ベッド移動台，１０５…ガイド，１１０…車内の床，１１１…除振台，１１２…アンカー，１１５…結合板，１１６…移動のための上部結合部，１１７…床，１１７−１…傾斜した床，１１８…車輪，１１９…移動ガイド溝，１２０，１２８…磁場遮蔽円筒支持体，１２２…椅子，１２４…ガントリ，１２６…クライオスタット位置固定ロック，１３０…磁場遮蔽装置支持体，１３１…クライオスタット保持板の固定台，１３２…クライオスタット保持板，１４０−１，１４０−２…スペーサ，１５０−１，１５０−２…結合板。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic field shielding device for measuring a magnetic field generated from an inspection object using a plurality of magnetometers composed of high-sensitivity quantum interference devices (SQUIDs), and magnetic field measurement using the same. The present invention relates to a method and a magnetic field measurement apparatus. The present invention particularly relates to a magnetic shielding device for measuring a biomagnetic field generated by myocardial activity of a heart of a living body, a biomagnetic field measurement method using the same, and a biomagnetic field measurement device.
[0002]
[Prior art]
There has been reported a magnetic shield in which a plurality of cylindrical shields having different diameters are sequentially arranged concentrically and a gap is formed between each cylindrical shield (conventional technology 1: Japanese Patent Laid-Open No. 9-214166).
[0003]
In the technique described in the prior art 1, a magnetic shield material made of tape-like permalloy having a thickness of 0.1 mm to 0.5 mm and a width of 20 cm to 50 cm is used, and the magnetic shield material is spirally formed with a lightweight plastic cylinder as a core. It is formed in a cylindrical shape with a width of 5 cm to 10 cm of the overlapped portion that is wound and overlapped without gaps. The overlap portion is substantially 2 to 5 layers, and is wound in a spiral shape so that the total thickness is about 0.5 mm to 3 mm. Also, the overlap portion is provided with rivets at intervals of 30 cm in the circumferential direction and fastened and fixed, and the adhesive surface of the overlap portion is in contact with metal.
[0004]
In the prior art 1, as a conventional technique, there is a description that a shield room such as a prefabricated room is manufactured using a large number of permalloy plates made of Ni-Fe-based high permeability alloy material. The conventional technology has a problem that it takes a long time to manufacture the magnetic shield, the number of parts is large, and the magnetic shield is very expensive. There is a description that lowering the price of the shield is desired.
[0005]
It has been reported that instead of a permalloy plate, a light shield room is produced using a magnetic shield sheet in which a soft magnetic amorphous alloy film and a polymer film are bonded together as a magnetic shield material (Prior Art 2). : JP-A 2000-077780).
[0006]
[Problems to be solved by the invention]
In the prior art of manufacturing a shield room by combining permalloy plates, the prior art 1 has a problem of requiring annealing of permalloy after processing, a problem of requiring a large area, a shield room having a large weight and a shield room. There was a problem that there was a restriction on the place where the camera was installed and a problem that the shield room was expensive. In the prior art 2, the weight of the shield room can be reduced and the price can be reduced compared to the prior art 1 in which the shield room is manufactured by combining the permalloy plates, but the problem of requiring a large area is solved. Therefore, it was desired to make the shield room lighter and cheaper.
[0007]
An object of the present invention is to provide a lightweight, small, high-performance magnetic field shielding device at a low cost by using a high permeability sheet having a high permeability, and to measure a magnetic field generated from a test object, particularly a living body. To provide a magnetic field measurement method and a magnetic field measurement apparatus.
[0008]
[Means for Solving the Problems]
A representative magnetic field measurement apparatus according to the present invention includes a magnetic field shielding device that shields a component in a direction perpendicular to a first direction of an external magnetic field, and a component in a direction perpendicular to the first direction of a magnetic field generated from an inspection target. A cryostat for holding a plurality of SQUID magnetometers for detecting the temperature, a device for holding the cryostat, a drive detection circuit for driving the SQUID magnetometer and detecting a signal from the SQUID magnetometer, and collecting the output of the drive detection circuit And an arithmetic processing unit that performs arithmetic processing and a display device that displays the output of the arithmetic processing unit.
[0009]
The magnetic field shielding device of the present invention is formed by arranging a plurality of nonmagnetic cylindrical members having hollow portions concentrically surrounding the axis in the first direction. A plurality of high-permeability sheets having high permeability are stuck and arranged on the surface (inner surface and / or outer surface) of each cylindrical member so as to partially overlap each other.
[0010]
The cylindrical member arranged at the innermost side has a first opening at one end in the first direction and a second opening at the other end in the first direction. A third opening penetrating the plurality of cylindrical members is formed in a direction perpendicular to the axis in the first direction. In the space inside the innermost cylindrical member, the component in the direction perpendicular to the first direction of the external magnetic field is shielded. When the inspection target is a living body, the living body (subject) is mounted in the space inside the cylindrical member arranged on the innermost side with the body axis direction of the inspection target part being substantially parallel to the axis in the first direction. Living body mounting devices (beds, chairs) are arranged.
[0011]
A part of the cryostat is inserted into the third opening, and the bottom surface of the cryostat is disposed in the inner space. Since the diameter of the third opening is made smaller than the diameter of the bottom surface of the cryostat and the portion where the diameter of the cryostat is small is inserted into the third opening, there is no need to increase the diameter of the third opening. The magnetic field shielding rate of the external magnetic field can be improved. When the test object is a living body, the third opening is opposed to the chest surface or the back surface of the living body (subject), and the bottom surface of the cryostat is opposed to the chest surface or the back surface of the living body. It is arranged in the space.
[0012]
The positional relationship between the bottom surface of the cryostat and the surface to be inspected is adjusted by the position adjusting device, and the positional relationship is adjusted in a direction perpendicular to the first direction. The position adjusting device can change the position of the cryostat or the position of the mounting device on which the inspection object is mounted in a second direction perpendicular to the first direction. Further, the position adjusting device can change the position of the mounting device in a third direction perpendicular to the first and second directions and in the first direction.
[0013]
Furthermore, the magnetic field shielding device is provided with a fourth opening penetrating each cylindrical member in a direction perpendicular to the axis of the first direction. When the inspection target is a living body, the fourth opening is formed. Is in the subject's field of view, giving the subject a sense of openness.
[0014]
[Embodiment]
In the following description, a living body heart will be described as a representative example as a test target. Needless to say, the present invention is not limited to the heart of a living body, and can be applied, for example, to the presence / absence of a magnetic substance included in a general examination object and the examination of the distribution of the magnetic substance. Since the configuration of the device of the present invention does not require a large area, it can be used, for example, as an inspection device for dangerous materials including magnetic materials, and can also be applied to baggage inspection at airfields, ports, and the like.
[0015]
The magnetic field shielding device of the present invention includes a plurality of high permeability sheets or Ni having a thin layer of a high permeability magnetic material composed of amorphous or polycrystalline, and having flexibility and thin thickness. A plurality of high-permeability sheets using a high-permeability magnetic material composed of an alloy containing the same are used. The high magnetic permeability sheet used in the present invention is flexible.
[0016]
In the plurality of high magnetic permeability sheets, a part of the high magnetic permeability sheet is disposed so as to overlap two to five non-magnetic cylindrical members having hollow portions. The plurality of cylindrical members are fixed to each other so as to concentrically surround the axis in the first direction. In a high permeability sheet, a region where a magnetic material is arranged is formed in a strip shape by being sandwiched between non-magnetic holding sheets (for example, paper, polymer film, metal film). The long sides of adjacent strips overlap, and the long sides of a plurality of strips are arranged almost in parallel.
[0017]
The short sides of the plurality of strips of each high permeability sheet are arranged substantially parallel to the axis in the first direction, and the high permeability sheet is disposed on the surface (inner surface and / or outer surface) of each of the plurality of cylindrical members. The long sides of the plurality of strips of the high permeability sheet are stuck and held so as to surround the axis in the first direction. By arranging a plurality of regions where magnetic materials having such strip shapes are arranged, the magnetic field shielding rate of the external magnetic field is improved.
[0018]
The innermost cylindrical member has a first opening at one end in the first direction and a second opening at the other end in the first direction. A third opening is formed into which a cryostat that penetrates the plurality of cylindrical members in a direction perpendicular to the first direction axis and holds the plurality of SQUID magnetometers at a low temperature is inserted. In the space inside the innermost cylindrical member, the component in the direction perpendicular to the first direction of the external magnetic field is shielded.
[0019]
A more preferable shape of the cross section perpendicular to the axis in the first direction of the plurality of cylindrical members is a highly symmetric shape from the viewpoint of improving the magnetic field shielding rate of the external magnetic field. For example, a shape crushed by about 10% of the diameter of the circle in a direction perpendicular to the axis of the direction 1 may be used.
[0020]
A more preferable shape of the cross section perpendicular to the axis in the first direction of the innermost cylindrical member is a circle having a diameter of about 50 cm or more and about 200 cm or less. Do not give a feeling of pressure to the subject inserted in the. In the case of a device dedicated to examining a child, the inner diameter of the cylindrical member disposed on the inside may be about 50 cm, and in the case of a device intended for testing children and large adults, it may be much longer. Also, the inner diameter of the cylindrical member disposed inside may be about 50 cm.
[0021]
As the plurality of non-magnetic cylindrical members, it is more preferable to use a FRP hollow cylinder or an aluminum hollow cylinder having a thickness of 0.5 mm to 1 mm from the viewpoint of manufacturing a magnetic field shielding device and cost.
[0022]
The subject is placed in a comfortable state in one of the following three modes in the space inside the cylindrical member arranged on the innermost side, in which the component in the direction perpendicular to the first direction of the external magnetic field is shielded. For example, a biomagnetic field generated from a fetus or the like in the subject's chest or abdomen is detected so that the body axis direction of the part of the subject to be detected is substantially parallel to the axis in the first direction. Is done.
(1) When the axis in the first direction is substantially horizontal with respect to the floor surface, the bed on which the subject lies is placed in the innermost cylindrical member in a substantially horizontal state. .
(2) In the case where the axis in the first direction is substantially perpendicular to the floor surface, the subject is placed inside the cylindrical member arranged on the innermost side while sitting on a chair.
(3) When the axis in the first direction is tilted at an angle of 20 degrees or more and 30 degrees or less with respect to the horizontal plane, the bed on which the subject lies is tilted or the chair on which the subject sits It is arranged inside the cylindrical member arranged on the innermost side with the angle of the backrest being inclined.
[0023]
The third opening and / or the fourth opening is formed in any of the following three modes. (1) A hole is formed in each cylindrical member, and a plurality of cylindrical members are fixed to each other so as to concentrically surround the shaft in the first direction, thereby integrating each cylindrical member. A third opening is formed by the hole. In addition to the aspect of (1), a part of each cylindrical member is configured to be movable, and the third and / or fourth openings are formed by movement of a part of each cylindrical member.
[0024]
That is, a part of each cylindrical member is movable in one of the first direction, the circumferential direction surrounding the axis in the first direction, and the direction crossing the first direction. The third and / or fourth opening is formed by the movement of the part. Specific embodiments are shown below.
(2) Each cylindrical member is divided into two parts, a first part and a second part, in the first direction. The cylindrical members of the first and second portions are configured to be fixed and integrated with each other so as to concentrically surround the axis in the first direction. The first part is separable by moving in the first direction relative to the second part.
[0025]
Each cylindrical member of the first portion has a first cutout portion having a semicircular portion opening at the end. Each cylindrical member of the second portion has a second notch having a semicircular portion opening at the end.
[0026]
As a result of the movement of the first part relative to the second part in the first direction, the end of the first part and the end of the second part overlap in the first direction, so that the first and second The third and / or fourth openings are formed by the notches.
[0027]
In addition to the first movement in the first direction relative to the second part of the first part, a second movement in the direction crossing the first direction is also possible. By the first movement, or the first movement and the second movement, an open portion is formed in the magnetic field shielding device.
(3) Each cylindrical member is divided into two parts, a first part and a second part, in a circumferential direction surrounding an axis in the first direction. The cylindrical members of the first and second portions are fixed and integrated with each other. The first portion is configured to be movable in a circumferential direction surrounding the second portion.
[0028]
Each cylindrical member of the first portion has a first cutout portion having a semicircular portion opening on one side substantially parallel to the first direction. Each cylindrical member of the second portion has a second cutout portion having a semicircular portion opening on one side substantially parallel to the first direction.
[0029]
Result of the first part and the second part overlapping in the circumferential direction surrounding the axis in the first direction by movement in the circumferential direction surrounding the axis in the first direction relative to the second part of the first part The third opening is formed by the first and second notches.
[0030]
The first portion and the second portion are overlapped in a range of about 10 degrees to about 15 degrees in the circumferential direction surrounding the axis in the first direction, with two sides substantially parallel to the first direction. Due to the movement of the first portion, an open portion in the range of about 90 degrees in the circumferential direction surrounding the axis in the first direction is formed in the magnetic field shielding device.
[0031]
In another configuration of the magnetic field shielding device, as described in (2) and (3) above, each cylindrical member is divided into two parts, a first part and a second part, The third opening is formed, but the third opening described above is not formed. The bottom of the cryostat is inserted from the first opening or the second opening. Since the fourth opening is formed at a position far from the examination target site of the subject, the magnetic field shielding rate of the external magnetic field is not deteriorated.
[0032]
The magnetic field measurement procedure in the present invention will be described below.
[0033]
First, a part of each cylindrical member of the magnetic shielding apparatus is opened by moving it in one of the first direction, the circumferential direction surrounding the axis in the first direction, and the direction crossing the first direction. Forming part.
[0034]
A living body is mounted on a living body mounting device (bed, chair) placed in a space inside the magnetic field shielding device through an opening from a direction crossing the axis of the first direction. Alternatively, the living body mounting device on which the living body is mounted moves along the axis in the first direction, the direction substantially parallel to the first direction, or the direction crossing the axis in the first direction through the open portion. It is carried into the space inside the shielding device.
[0035]
Next, a part of each cylindrical member is moved in one of the first direction, the circumferential direction surrounding the axis in the first direction, and the direction crossing the first direction, thereby closing the open portion. To do. As a result, a third and / or fourth opening is formed, and a part of the cryostat is inserted into the third opening.
[0036]
The positional relationship between the bottom surface of the cryostat arranged in the space inside the magnetic field shielding device and the surface of the living body is adjusted in a direction perpendicular to the first direction so that a magnetic field signal is detected largely. A plurality of SQUID magnetometers detect a component in a direction perpendicular to the first direction of the magnetic field generated from the living body.
[0037]
According to the present invention, a light-weight, compact, low-cost, high-performance, magnetic field shielding device having a high magnetic field shielding rate of an external magnetic field can be provided, and further, a biomagnetic field using this magnetic field shielding device can be measured. Magnetic field measuring method and magnetic field measuring apparatus can be provided.
[0038]
In addition, since the magnetic field shielding device of the present invention is light and small, load resistance is not particularly required at the place of installation, and installation is possible if there is a small area. There are no restrictions on where to install the equipment.
[0039]
Here, it is assumed that the time variable is t, the surface of the living body is the (x, y) plane, and the direction perpendicular to the surface of the living body is the z direction. The position of the SQUID magnetometer that is arranged in a two-dimensional grid pattern at equal intervals in the vicinity of the bottom inside the cryostat (x, y), and the magnetic field component (normal component) of the biomagnetic field detected by the SQUID magnetometer Let Bz (x, y, t).
[0040]
In the magnetic field measurement apparatus of the present invention, the tangential components Bx (x, y, t) and By (x, y, t) of the biomagnetic field are respectively measured in the x direction of the measured normal component Bz (x, y, t). The rate of change ∂Bz (x, y, t) / ∂x, y is obtained as a value proportional to the rate of change ∂Bz (x, y, t) / ∂y in the y direction. When the proportionality constant is 1, the tangential components Bx (x, y, t) and By (x, y, t) are given by (Equation 1) and (Equation 2).
[0041]
[Expression 1]
Bx (x, y, t) = − (∂Bz (x, y, t) / ∂x) (Equation 1)
[0042]
[Expression 2]
By (x, y, t) = − (∂B (x, y, t) z / ∂y) (Expression 2)
Next, a value St (x, y, t) proportional to the square root of the sum of squares of the change rate in the x direction and the change rate in the y direction is obtained. When the proportionality constant is 1, the magnetic field waveform St (x, y, t) is given by (Equation 3).
[0043]
[Equation 3]
St (x, y, t) = √ [{∂Bz (x, y, t) / ∂x} 2+ {∂Bz (x, y, t) / ∂y} 2] (Equation 3)
St (x, y, t) gives magnetic field strength information obtained by projecting the magnetic field generation source inside the living body onto the (x, y) plane. The peak position of each wave of Q, R, S is taken as t, and isomagnetic field lines connecting (x, y) points that give the same magnetic field strength by interpolation and extrapolation from the data of St (x, y, t) Ask for a figure.
[0044]
Next, for each point (x, y), an integral value I (x, y) of the magnetic field waveform St (x, y, t) in an arbitrary period is obtained by (Equation 4) and integrated by interpolation and extrapolation. An isointegral diagram connecting points having the same value I (x, y) is obtained.
[0045]
As an integration range, for example, when the heart is to be measured, a Q wave, a R wave, and a S wave are generated, a Q wave is a QRS wave (QRS complex), and a T wave is generated. Take a period.
[0046]
[Expression 4]
I (x, y) = ∫ | St (x, y, t) | dt (Equation 4)
Further, by calculating the time waveform V (x, y, t) of the magnetic field intensity obtained by synthesizing the magnetic field components in the three directions of x, y, and z by (Equation 5), especially when the movement is intense like a fetus. However, a stable magnetic field waveform can be obtained.
[0047]
[Equation 5]
V (x, y, t) = √ [{∂Bz (x, y, t) / ∂x} 2+ {∂Bz (x, y, t) / ∂y} 2+ {Bz (x, y, t) } 2] ... (Formula 5)
Using V (x, y, t) instead of St (x, y, t), isomagnetic field diagrams and integral diagrams can be obtained in the same manner as described above.
[0048]
The magnetic field waveforms St (x, y, t) and V (x, y, t) measured by each SQUID magnetometer are displayed, and as a magnetic field distribution diagram, an isomagnetic field diagram and an integral diagram are displayed. Display on the display screen. Isomagnetic field diagrams and integral diagrams are color-coded according to the level of their contour lines and displayed in three-dimensional color to obtain data useful for diagnosis.
[0049]
That is, in the magnetic field measurement apparatus of the present invention, only the normal component Bz (x, y, t) is measured without measuring the tangential components Bx (x, y, t) and By (x, y, t). Thus, a magnetic field distribution map in which a peak pattern appears immediately above the current source can be obtained. As a result, the position of multiple current sources in the living body can be read directly, so that it can be used for diagnosis of heart diseases such as myocardial infarction, ischemia, arrhythmia, myocardial hypertrophy, and evaluation of changes in myocardial state before and after surgery. Useful data can be obtained. In particular, the magnetic field measurement apparatus of the present invention can measure and display data (magnetic field distribution) for diagnosis of adult and fetal hearts in a short time of about 10 seconds to 5 minutes.
[0050]
Hereinafter, more specifically, representative examples will be described in detail with reference to the drawings.
[0051]
FIG. 1 is a diagram for explaining a configuration example of a high permeability sheet 23 having a high permeability used in each embodiment of the present invention. FIG. 2 is a perspective view for explaining an arrangement example of the high magnetic permeability sheet on the hollow cylinder constituting the magnetic field shielding device in each embodiment of the present invention. FIG. 3 is a cross-sectional view for explaining an arrangement example of the high magnetic permeability sheet in the hollow cylinder constituting the magnetic field shielding device in each embodiment of the present invention.
[0052]
The flexible high magnetic permeability sheet 23 is configured by sandwiching a magnetic material 25 (magnetic material ribbon, magnetic material tape) 25 between non-magnetic holding sheets 26-1 and 26-2. This high magnetic permeability sheet 23 is the same as the high magnetic permeability sheet described in Prior Art 2. A soft magnetic amorphous alloy is used as the high magnetic permeability material.
[0053]
The strip-shaped magnetic material ribbons 25 are arranged so as to overlap the long sides of adjacent strips, and the long sides of the plurality of strips are arranged substantially in parallel. The plurality of magnetic material ribbons 25 are fixed between the holding sheets 26-1 and 26-2 by a flexible resin or an adhesive 24. As a material for the holding sheets 26-1 and 26-2, a PET (polyethylene terephthalate) sheet is typically used. The size of the high magnetic permeability sheet 23 is, for example, 450 cm long and 600 cm wide.
[0054]
The soft magnetic amorphous alloy is Fe-Cu-Nb-Si-B system having a maximum relative permeability of 50000 or more (Fe: 73.5%, Cu: 1%, Nb: 3%, Si: 13.5%, B: 9%) and has an ultrafine crystal structure with a grain boundary size of 100 nm or less.
[0055]
The magnetic material ribbon 25 used has a thickness of about 20 μm, the holding sheets 26-1 and 26-2 have a thickness of 30 μm, and the high permeability sheet 23 has a total thickness of 100 μm. When the thickness of the magnetic material ribbon 25 is about 10 μm to 100 μm, the thickness of the holding sheets 26-1 and 26-2 is 10 μm to 500 μm, and the total thickness of the high magnetic permeability sheet 23 is 50 μm to 1.5 mm, The magnetic sheet 23 can be attached and bent easily.
[0056]
The magnetic field shielding device in each embodiment of the present invention includes a plurality of magnetic field shielding cylinders 60 arranged coaxially. Each magnetic field shielding cylinder includes a high permeability sheet support cylinder 80 having different inner radii and a high permeability sheet layer 82 disposed on the inner peripheral surface and / or outer peripheral surface of the high permeability sheet support cylinder 80.
[0057]
In each magnetic field shielding cylinder, a circular third opening 43 for inserting the bottom surface of the cryostat is formed in the innermost magnetic field shielding cylinder corresponding to each embodiment. A circular fourth opening 44 is formed in the field of view of the patient located inside the magnetic field shielding cylinder to allow the patient to interact with the physician in line of sight.
[0058]
FIG. 2 shows one magnetic field shielding cylinder 60, and a plurality of high permeability sheets 23 are bonded to the outer peripheral surface of the high permeability sheet support cylinder 80 by using an adhesive or the like to form a high permeability sheet layer 82. Is formed. The high permeability sheet support cylinder 80 uses an aluminum hollow cylinder having an inner radius r and a thickness of 0.5 mm.
[0059]
The high magnetic permeability sheet 23 is attached by any one of the following methods. (1) A plurality of high permeability sheets 23 are pasted so as to have overlapping portions. (2) The upper high-permeability sheet 23 is attached so as to cover the overlapping portion of the lower high-permeability sheet 23. (3) Affix by combining the method of (1) and the method of (2). In any of the pasting methods, a plurality of high magnetic permeability sheets 23 are stuck and pasted so that the portions of the magnetic material ribbon 25 overlap each other due to the mutual overlap of the high magnetic permeability sheets 23.
[0060]
Each high magnetic permeability sheet 23 has a long side of each magnetic material ribbon 25 that is a central axis of the holding cylinder 21 such that a short side of each magnetic material ribbon 25 is substantially parallel to the central axis of the high magnetic permeability sheet support cylinder 80. Is attached to the high permeability sheet support cylinder 80 with an adhesive or the like so as to be substantially parallel to a plane perpendicular to the central axis of the high permeability sheet support cylinder 80. A plurality of layers are formed.
[0061]
FIG. 3 shows a high magnetic permeability sheet layer 82 formed by two layers of high magnetic permeability sheets 23. In FIG. 3, the overlap of the high permeability sheet 23 in each of the first layer and the second layer is omitted.
[0062]
In the magnetic field shielding apparatus in each embodiment of the present invention, the high magnetic permeability sheet support cylinder 80 constituting each of the plurality of magnetic field shielding cylinders 60 arranged coaxially has different inner radii. The interval between adjacent high magnetic permeability sheet support cylinders 80 is 1 cm to 20 cm. With the configuration of the magnetic field shielding device described above, the external magnetic field component is shielded with a high magnetic field shielding rate inside the innermost magnetic field shielding cylinder with respect to the component perpendicular to the central axis of the plurality of magnetic field shielding cylinders 60 of the external magnetic field. In the following embodiments, to simplify the drawing, the configuration of a magnetic field shielding device having two magnetic field shielding cylinders is illustrated, but the configuration of a magnetic field shielding device having two to five magnetic field shielding cylinders may be used. good.
[0063]
In the following description of each embodiment, the central axis of a plurality of magnetic field shielding cylinders 60 arranged coaxially is referred to as “the central axis of the magnetic field shielding device” for simplicity. Furthermore, in the following description of each embodiment, each of the plurality of magnetic field shielding cylinders 60 is divided into two parts in the direction perpendicular to the central axis, or two parts in the circumferential direction. Even when each of the plurality of magnetic field shielding cylinders 60 is configured by overlapping these two portions with each other, a plurality of the plurality of magnetic field shielding cylinders 60 are arranged and arranged coaxially. Similarly, the central axis of the magnetic field shielding cylinder is called “the central axis of the magnetic field shielding device”.
Example 1
FIG. 4 is a perspective view illustrating a configuration example of the biomagnetic field measurement apparatus according to the first embodiment of the present invention. FIG. 5 is a perspective view of the magnetic shielding apparatus 40 shown in FIG. 6 is a cross-sectional view taken along a plane passing through the center of the measurement visual field of the biomagnetic field measurement apparatus shown in FIG.
[0064]
The biomagnetic field measurement apparatus includes a magnetic shielding apparatus 40, a cryostat 50 that holds a plurality of SQUID magnetometers 57 that detect a magnetic field (biomagnetic field) generated from an inspection target (living body), and a gantry 30- that supports the cryostat 50. 2, a magnetic field shielding device / gantry support base 30-1 for supporting the magnetic field shielding device 40 and the gantry 30-2, a refrigerant supply device or cooling device 55 for cooling the inside of the cryostat 50, and a refrigerant supply line or cooling transmission. A data collection processing / sensor control device 52 that collects the detected biomagnetic field by performing drive control of the SQUID magnetometer 57 via the line 54 and the data collection / sensor control line 51, and displays the result of the data processing. It is composed of one or a plurality of display devices 53.
[0065]
The inside of the cryostat 50 is cooled by the liquid He supplied from the refrigerant supply device 55 via the refrigerant supply line 54 or by using a refrigerator as the cooling device 55 via the cooling transmission line 54 by a compressor. The cooled He gas is supplied to a cold head arranged inside the cryostat 50 to be cooled.
[0066]
The magnetic field shielding device 40 includes a plurality of magnetic field shielding cylinders 60 described with reference to FIGS. 2 and 3, and the first opening 41 is formed in the positive direction of the central axis (y direction) of the plurality of magnetic field shielding cylinders in the y direction. Inspection that lies on the bed 20 has a second opening 42 in the negative direction and a third opening 43 that penetrates the plurality of magnetic shielding cylinders for inserting the cryostat 50 in the upper part in the direction perpendicular to the central axis (z direction). Each has a fourth opening 44 penetrating a plurality of magnetic shielding cylinders for observing the object. The central axis (y direction) of the plurality of magnetic field shielding cylinders (the central axis of the magnetic field shielding device 40) is horizontal to the floor surface.
[0067]
The magnetic field shielding device 40 shields the component of the external magnetic field perpendicular to the central axis of the magnetic field shielding device 40 inside the innermost magnetic field shielding cylinder 60-1 with a high magnetic field shielding rate. As a result, the SQUID magnetometer 57 can detect the z-direction component of the biomagnetic field generated inside the magnetic field shielding device 2 with high sensitivity.
[0068]
The height of the gantry 30-2 is controlled and fixed by the height control device 31 of the gantry, and the examiner (physician) 35 moves the examination part (patient) 36 lying on the bed 20 through the fourth opening 44 and the cryostat 50. The height control box 32 of the gantry is operated while observing the positional relationship with the bottom surface of the gantry. The gantry height control device 31 is controlled by a signal from the gantry height control box 32, and the position of the bottom surface of the cryostat 50 in the z direction is fixed. The x direction is set to a direction orthogonal to the y direction and the z direction.
[0069]
A plurality of SQUID magnetometers 57 arranged in a plane (measurement plane) parallel to the xy plane in the vicinity of the bottom inside the cryostat 102 are driven by the FLL circuit of the data collection processing / sensor control device 52. The FLL circuit outputs a biomagnetic field signal detected by the SQUID magnetometer 57. The output of the FLL circuit is filtered, amplified, converted into digital data by an AD converter, and stored in the storage device of the data collection processing / sensor control device 52. As a result of data processing by the data collection processing / sensor control device 52, for example, magnetic field waveform St (x, y, t) ((Equation 3)), V (x, y, t) ((Equation 5)), etc. A magnetic field diagram, an integral diagram, and the like are displayed on the display screen of the display device 53.
[0070]
The bed 20 on which the inspection object 36 is mounted is mounted on the x and y direction moving device 21, and the x and y direction moving device 21 is fixed to the support base 22 of the x and y direction moving device. The bed 20 is disposed inside the innermost magnetic field shielding cylinder of the magnetic field shielding device 40.
[0071]
Note that an x, y, z direction moving device can be used instead of the x and y direction moving device 21 with the height of the bottom surface of the cryostat 50 fixed. In this case, the positional relationship between the gantry 30-2 and the magnetic field shield device 40 is such that the measurement surface on which the detection coils of the plurality of SQUID magnetometers 57 are arranged is substantially the central axis of the innermost magnetic field shield cylinder 60-1. The position of the gantry 30-2 is fixed so as to match, or the gantry 30-2 and the magnetic shielding device / gantry support base 30-1 are integrally configured. Of course, the gantry height control device 31 and the gantry height control box 32 are not required.
[0072]
The examiner (doctor) 35 enters the height control box 32 of the gantry while observing the positional relationship between the examination portion of the examination target (patient) 36 on the bed 20 and the bottom surface of the cryostat 50 through the fourth opening 44. Instead, an x, y, z direction movement control box (not shown) of the bed 20 is operated. A signal from the x, y, z direction movement control box controls the x, y, z direction moving device of the bed 20, and the position of the bed 20 in the x direction, y direction, and z direction is fixed.
[0073]
In the above description, the examiner (physician) 35 observes the patient 36 through the fourth opening 44, but the patient does not pass through the first opening 41 or the second opening 42 as a configuration in which the fourth opening 44 is not provided. It goes without saying that 36 may be observed.
[0074]
The fourth opening 44 provided in the field of view of the patient 36 gives the patient 36 a feeling of opening, and the examiner (doctor) 35 can interact with the patient 36 through the fourth opening 44 and can accurately interact with the patient 36. Can be observed. The examiner (doctor) 35 can easily transmit instructions to the patient 36. The patient 36 can see the outside of the magnetic shielding apparatus 40 through the fourth opening 44, and has an effect of reducing psychological anxiety and the like.
[0075]
As shown in FIG. 5, the central axis of the third opening 43 that penetrates the plurality of magnetic field shielding cylinders and the central axis of the fourth opening 44 that penetrates the plurality of magnetic field shielding cylinders form an angle of about 45 degrees. There is no. As shown in FIG. 6, SQUID magnetometers 57 are two-dimensionally arranged at the bottom inside the cryostat 50, and the cryostat 50 is filled with a refrigerant 56.
[0076]
The magnetic field shielding cylinder 60 includes a first magnetic field shielding cylinder 60-1 and a second magnetic field shielding cylinder 60-2. A filler 70 is filled between the first magnetic field shielding cylinder 60-1 and the second magnetic field shielding cylinder 60-2, and the first magnetic field shielding cylinder 60-1 and the second magnetic field shielding cylinder 60-. The shape of 2 is stably maintained. In the example shown in FIG. 6, the filler 70 is filled in the lower half. However, the upper half portion excluding the third opening 43 and the fourth opening 44 may be filled. As the filler 70, hard polyurethane containing a foaming agent or the like can be used. Since the hard polyurethane containing the foaming agent is lightweight, the first magnetic field shielding cylinder 60-1 and the second magnetic field shielding cylinder can be filled even in the upper half portion excluding the third opening 43 and the fourth opening 44. The shape of 60-2 is not changed.
(Example 2)
FIG. 7 is a perspective view showing a configuration example of the biomagnetic field measurement apparatus according to the second embodiment of the present invention. FIG. 8 is a perspective view of the magnetic shielding apparatus shown in FIG. FIG. 9 is a cross-sectional view taken along a plane passing through the center of the measurement visual field of the biomagnetic field measurement apparatus shown in FIG. 7, and includes a partially enlarged cross section.
[0077]
Hereinafter, the difference from the first embodiment will be mainly described. In the configuration of the biomagnetic field measurement device according to the second embodiment, the magnetic field shielding device 40 described in the first embodiment is divided into two in the y direction, and the first portion 40-1 of the magnetic field shielding device and the second of the magnetic field shielding device. Part 40-2. The first part 40-1 of the magnetic shielding apparatus is configured to be movable in the y direction with respect to the second part 40-2 of the magnetic shielding apparatus. Similar to the first embodiment, the gantry 30-2 and the second portion 40-2 of the magnetic shielding apparatus are supported by the magnetic shielding apparatus / gantry support 30-1.
[0078]
The first portion 40-1 of the magnetic field shielding device is supported and fixed to the magnetic field shielding device support base 92, and the plurality of wheels 91 disposed below the magnetic field shielding device support base 92 are disposed on the surface of the floor 117. It is mounted on rails 90-1 and 90-2. The first part 40-1 of the magnetic shielding apparatus can move in the y direction on the rails 90-1 and 90-2. By this movement, the first portion 40-1 of the magnetic field shielding device and the second portion 40-2 of the magnetic field shielding device can be separated.
[0079]
As a result, in the open space, the doctor 35 can mount the patient 36 on the bed 20 in an easy posture, or the patient 36 can lie down on the bed 20 easily. The patient is mounted so that the foot passes first through the lower part of the cryostat and finally the chest reaches the lower part of the cryostat. The doctor 35 can efficiently adjust the positional relationship between the examination site of the patient 36 and the bottom surface of the cryostat 50. After the adjustment, the separated first part 40-1 of the magnetic field shielding apparatus is moved, and the first part 40-1 of the magnetic field shielding apparatus and the second part 40-2 of the magnetic field shielding apparatus are moved in the y direction. By overlapping, the third opening 43 and the fourth opening 44 can be formed.
[0080]
As a result, a component perpendicular to the central axis of the external magnetic field shielding device 40 can be shielded with a high magnetic field shielding rate inside the innermost magnetic field shielding cylinders 40-1-1 and 40-2-1. In the space where the external magnetic field is shielded with a high magnetic field shielding rate, the z-direction component of the biomagnetic field from the examination site can be detected with high sensitivity.
[0081]
As shown in FIG. 8, when the magnetic field shielding cylinder constituting the first part 40-1 of the magnetic field shielding apparatus and the magnetic field shielding cylinder constituting the second part 40-2 of the magnetic field shielding apparatus are respectively overlapped, In order to form the third opening 43 and the fourth opening 44, it has a notch portion having a part of the circumference.
[0082]
As shown in FIG. 9, the magnetic shielding device 40 includes a first portion 40-1 of the magnetic shielding device and a second portion 40-2 of the magnetic shielding device. The first part 40-1 of the magnetic field shielding device is composed of a first magnetic field shielding inner cylinder 40-1-1 and a first magnetic field shielding outer cylinder 40-1-2. The second part 40-2 of the magnetic field shielding device is composed of a second magnetic field shielding inner cylinder 40-2-1 and a second magnetic field shielding outer cylinder 40-2-2.
[0083]
A first magnetic field shielding outer cylinder 40-1-2 is disposed inside the second magnetic field shielding outer cylinder 40-2-2, and is disposed inside the second magnetic field shielding outer cylinder 40-2-1. , The first magnetic field shielding inner cylinder 40-1-1 is overlapped. FIG. 9 shows a third opening at this overlapping portion.
[0084]
As shown in the enlarged cross section, the high magnetic permeability sheet 23 is provided inside the high magnetic permeability sheet support cylinder 80 of the second magnetic field shielding inner cylinder 40-2-1 and the second magnetic field shielding outer cylinder 40-2-2. Thus, the high magnetic permeability sheet layer 82 is formed. The high magnetic permeability sheet 23 is provided on the outer side of the high magnetic permeability sheet support cylinder 80 of the first magnetic field shield inner cylinder 40-1-1 and the first magnetic field shield outer cylinder 40-1-2. Is formed. As a result, in the overlapping portion, the high magnetic permeability sheet layer 82 is brought close to each other, so that the leakage magnetic flux is reduced and the magnetic field shielding effect is enhanced.
[0085]
Also, a second magnetic field shielding outer cylinder 40-2-2 and a first magnetic field shielding outer cylinder 40-1-2 outside the third opening in a direction parallel to the central axis of the magnetic field shielding device 40, The overlapping distance between the second magnetic field shielding inner cylinder 40-2-1 and the first magnetic field shielding inner cylinder 40-1-1 is about ½ to about the diameter of the third opening. 1/4. The overlapping portion is made sufficiently large to enhance the magnetic field shielding effect.
[0086]
The bed 20 on which the bed 20, the x- and y-direction moving devices 21 are mounted and the support base 22 of the moving device are disposed inside the second magnetic field shielding inner cylinder 40-2-1 via the spacer 140-1. For the same purpose as in the first embodiment, the lower half between the second magnetic field shielding inner cylinder 40-2-1 and the second magnetic field shielding outer cylinder 40-2-2 is filled with the filler 70-1. The lower half between the first magnetic field shielding inner cylinder 40-1-1 and the first magnetic field shielding outer cylinder 40-1-2 is filled with a filler 70-2. In the example shown in FIG. 9, the fillers 70-1 and 70-2 are filled in the lower half, but the upper half portions excluding the third opening 43 and the fourth opening 44 may be filled. It goes without saying that it is good.
[0087]
As in the first embodiment, the x, y, z direction moving device of the bed 20 can be used in place of the x and y direction moving device 21 with the height of the bottom surface of the cryostat 50 fixed. Needless to say. Furthermore, it goes without saying that the fourth opening may be omitted as in the first embodiment.
(Example 3)
FIG. 10 is a perspective view illustrating a configuration example of the biomagnetic field measurement apparatus according to the third embodiment of the present invention. FIG. 11 is a perspective view of the magnetic shielding apparatus shown in FIG. 10 and includes a partially enlarged cross section. FIG. 12 is a cross-sectional view for explaining taking in and out of a test object (patient) to and from the biomagnetic field measurement apparatus shown in FIG. 7, and includes a partially enlarged cross section.
[0088]
Hereinafter, the difference from the first embodiment will be mainly described. The magnetic field shielding device 40 described in the first embodiment is divided into two in the circumferential direction, and is configured by a first portion 40-3 of the magnetic field shielding device and a second portion 40-4 of the magnetic field shielding device. The first part 40-3 of the magnetic shielding apparatus is configured to be movable in the circumferential direction with respect to the second part 40-4 of the magnetic shielding apparatus. As in the first embodiment, the gantry 30-2 and the second part 40-4 of the magnetic shielding apparatus are supported by the magnetic shielding apparatus / gantry support 30-1.
[0089]
As shown in FIGS. 11 and 12, the first part 40-3 of the magnetic field shielding device is coupled to the first magnetic field shielding unit 150-1 by the coupling plate 150-1 at the positive and negative ends in the y direction. It is composed of an inner cylinder 40-3-1 and a second magnetic field shielding outer cylinder 40-3-2. Similarly, the second portion 40-4 of the magnetic field shielding device of the magnetic field shielding device is coupled by a coupling plate 150-2 (not shown) at the positive and negative ends in the y direction. It comprises a magnetic field shield inner cylinder 40-4-1 and a second magnetic field shield outer cylinder 40-4-2. As shown in FIGS. 10, 11, and 12, a fourth opening 40 penetrating the first magnetic field shielding inner cylinder 40-3-1 and the second magnetic field shielding outer cylinder 40-3-2 is formed. Yes.
[0090]
The inside of the first magnetic field shielding inner cylinder 40-3-1 and the outer side of the second magnetic field shielding outer cylinder 40-3-2 of the fourth opening 40 are each covered with a transparent curved plate. When the circumferential movement of the first portion 40-3 of the magnetic field shielding device relative to the second portion 40-4 of the magnetic field shielding device is performed, hands, clothes, and the like are not caught.
[0091]
The first part 40-3 of the magnetic field shielding apparatus has a circumference of about 110 degrees, and the second part 40-4 of the magnetic field shielding apparatus has a circumference part of about 270 degrees, and is mutually opposite at both ends. It is set as the structure which overlaps in the range of about 10 degree | times. That is, the first magnetic field shielding inner cylinder 40-3-1 and the second magnetic field shielding inner cylinder 40-4-1, and the second magnetic field shielding outer cylinder 40-3-2 and the second magnetic field shielding outer cylinder. When 40-4-2 overlaps in the range of about 10 degrees at both ends parallel to the central axis of the magnetic field shielding device, it forms a closed magnetic field shielding device and overlaps in the range of about 110 degrees. , Forming an open magnetic field shielding device. In the closed state, the overlapping portion is made sufficiently large to enhance the magnetic field shielding effect.
[0092]
On the outer peripheral surface of the high permeability sheet supporting cylinder 80 of the second magnetic field shielding outer cylinder 40-3-2, a T-shaped elongated plate is arranged as a guide 105-2 as shown in an enlarged cross section. In addition, a T-shaped elongated groove for receiving the guide 105-2 is formed on the inner peripheral surface of the high permeability sheet supporting cylinder 80 of the second magnetic field shielding outer cylinder 40-4-2.
[0093]
Similarly, a T-shaped elongated plate is arranged as a guide 105-1 on the outer peripheral surface of the high permeability sheet supporting cylinder of the first magnetic field shielding inner cylinder 40-3-1. A T-shaped elongated groove (not shown) for receiving the guide 105-1 is formed on the inner peripheral surface of the high permeability sheet supporting cylinder of the magnetic field shielding inner cylinder 40-4-1.
[0094]
Note that the high magnetic permeability sheet 23 causes the high magnetic permeability sheet layer 82 to correspond to the high magnetic permeability sheet supporting cylinders of the second magnetic field shielding inner cylinder 40-4-1 and the second magnetic field shielding outer cylinder 40-4-2. On the outer surface, the first magnetic field shielding inner cylinder 40-3-1 and the second magnetic field shielding outer cylinder 40-3-2, respectively, are formed on the inner surfaces of the high permeability sheet supporting cylinders.
[0095]
As shown in FIG. 11, when the magnetic field shielding cylinder constituting the first part 40-3 of the magnetic field shielding apparatus and the magnetic field shielding cylinder constituting the second part 40-4 of the magnetic field shielding apparatus are respectively overlapped, 3 has a notch portion having a part of the circumference so as to form the three openings 43.
[0096]
FIG. 12A shows a state where the patient 36 lies on the bed 20 and the biomagnetic field from the examination site is measured. The magnetic field shielding cylinder constituting the first part 40-3 of the magnetic field shielding apparatus and the magnetic field shielding cylinder constituting the second part 40-4 of the magnetic field shielding apparatus overlap each other. The positional relationship between the first portion 40-3 and the second portion 40-4 is fixed by a lock. In this state, the component perpendicular to the central axis of the magnetic field shielding device 40 of the external magnetic field can be shielded with a high magnetic field shielding rate inside the innermost magnetic field shielding cylinders 40-3-1 and 40-4-1. In the space where the external magnetic field is shielded with a high magnetic field shielding rate, the z-direction component of the biomagnetic field from the examination site can be detected with high sensitivity.
[0097]
FIG. 12 (b) shows that the first part 40-3 of the magnetic field shielding device moves in the circumferential direction manually or automatically using a handle (not shown) attached to the first part 40-3. Then, the position of the first portion 40-3 is locked, an opening is formed, and an open space is formed in an angle range of about 90 degrees. As a result, in the open space, the doctor 35 can easily mount the patient 36 on the bed 20 from the bed moving table 103, or the patient 36 can easily lie on the bed 20, and the doctor 35 can check the patient 36. The positional relationship between the part and the bottom surface of the cryostat 50 can be adjusted efficiently.
[0098]
As in the first embodiment, the x, y, z direction moving device of the bed 20 can be used in place of the x and y direction moving device 21 with the height of the bottom surface of the cryostat 50 fixed. Needless to say. Furthermore, it goes without saying that the fourth opening may be omitted as in the first embodiment.
(Example 4)
The biomagnetic field measurement apparatus according to the fourth embodiment of the present invention is a bedside biomagnetic field measurement apparatus having a configuration in which a part of the configuration of the biomagnetic field measurement apparatus according to the third embodiment is changed and movable to the vicinity of a bed in a hospital room. is there.
[0099]
A plurality of wheels 100 are arranged on the magnetic shielding device / gantry support base 30-1 so as to be movable, and a plurality of wheels are also arranged so as to be movable on the bed and the support base 22 of the movement device. 29-1, 29-2, 29-3, 29-4 (not shown) are arranged. A data collection processing / sensor control device 52, a display device 53, a refrigerant supply device or a cooling device 55 is mounted on a plurality of carts having 100-1.
[0100]
In the bedside biomagnetic field measurement apparatus according to the fourth embodiment, the height of the bottom surface of the cryostat 50 is fixed, and the x, y, z direction moving device 21 of the bed 20 is used instead of the x and y direction moving device 21. Use '.
[0101]
As shown in FIG. 12 (c), wheels 29′-1, 29′-2, 29′-3 (not shown), 29′-4 (not shown) are provided, After the bedside biomagnetic field measuring device is moved in the vicinity, as shown in FIG. 12B, the first portion 40-3 of the magnetic field shielding device is moved in the circumferential direction, and its position is locked. An open space is formed in an angle range of 90 degrees.
[0102]
Using the bed 20 x, y, z direction moving device 21 ′ of the bedside biomagnetic field measuring device and the bed 20-1, x, y, z direction moving device 21 ′ of the bed moving table 10, x The patient 36 can be easily moved from the bed 20-1 to the bed 20 by adjusting the positions of the bed 20 and the bed 20-1 in each of the, y, and z directions.
[0103]
Using the bed 20-1, x, y, z direction moving device 21 ′, the doctor 35 adjusts the positional relationship between the examination site of the patient 36 and the bottom surface of the cryostat 50. Thereafter, in the state shown in FIG. 12A, the biomagnetic field from the examination site of the patient 36 is measured. After the measurement of the biomagnetic field, as shown in FIG. 12B, the x, y, z direction moving device 21 ′ of the bed 20 and the bed 20-1, x, y, z direction moving device of the bed moving table 10 are obtained. 21 ′ and adjust the position of the bed 20 and the bed 20-1 in each of the x, y, and z directions to easily move the patient 36 from the bed 20 to the bed 20-1. Can do.
[0104]
The biomagnetic field measuring apparatus for bedside of Example 4 can move freely, and can move in the hospital and inspect the hospitalized patient at the bedside. Therefore, when measuring an emergency patient or a bedridden patient, the patient does not need to move to the examination room where the biomagnetic field measuring apparatus is installed, and the burden on the patient is reduced.
(Example 5)
FIG. 13 shows an embodiment of the fifth embodiment of the present invention, and a part showing an example of a medical examination vehicle (mobile biomagnetic field measurement device) in which the biomagnetic field measurement device described in the third or fourth embodiment is mounted on an automobile. It is a perspective view containing a fracture | rupture part. The entire biomagnetic field measuring apparatus is arranged and fixed on a vibration isolation table 111 placed on a floor 110 in the vehicle, and blocks external vibrations. The automobile is provided with an anchor 112 for fixing, and when measuring a biomagnetic field, the anchor 112 is lowered to the ground to fix the automobile to the ground. This examination car is moved to local communities such as schools and public health centers and used for regular group examinations.
(Example 6)
FIG. 14 is a perspective view showing a configuration example of a magnetic shielding apparatus used in the biomagnetic field measurement apparatus according to Embodiment 6 of the present invention, and includes a partial enlargement. FIG. 15 is a cross-sectional view taken along a plane passing through the center of the measurement field of the biomagnetic field measurement apparatus using the magnetic field shielding apparatus shown in FIG.
[0105]
The magnetic field shielding apparatus shown in FIG. 14 divides the magnetic field shielding apparatus 40 described in the first embodiment into two parts in the circumferential direction, and the first part 40-5 of the magnetic field shielding apparatus and the second part 40- of the magnetic field shielding apparatus. 6. The first part 40-5 of the magnetic shielding apparatus is configured to be movable in the circumferential direction with respect to the second part 40-6 of the magnetic shielding apparatus.
[0106]
A plurality of wheels 118 are fixed to the lower part of the second magnetic field shielding inner cylinder 40-6-1 and the second magnetic field shielding outer cylinder 40-6-2, and as shown in the enlarged cross section of FIG. 118 is arranged inside a movement guide groove 119 formed in the floor 117. The upper portions of the second magnetic field shielding inner cylinder 40-6-1 and the second magnetic field shielding outer cylinder 40-6-2 are coupled by a coupling plate 115. On the coupling plate 115, an upper coupling portion 116 for movement for coupling to a circular guide rail disposed on the ceiling is fixed.
[0107]
As shown in the enlarged cross section of FIG. 14, a high permeability is provided inside each high permeability sheet support cylinder 80 of the second magnetic field shielding inner cylinder 40-6-1 and the second magnetic field shielding outer cylinder 40-6-2. A high permeability sheet layer 82 is formed by the magnetic permeability sheet 23. A high magnetic permeability sheet 23 provides a high magnetic permeability sheet layer 82 on the outer side of each high magnetic permeability sheet support cylinder 80 of the first magnetic field shield inner cylinder 40-5-1 and the first magnetic field shield outer cylinder 40-5-2. Is formed. As a result, in the overlapping portion, the high magnetic permeability sheet layer 82 is brought close to each other, so that the leakage magnetic flux is reduced and the magnetic field shielding effect is enhanced.
[0108]
As shown in FIG. 15, the first magnetic field shielding inner cylinder 40-5-1 is provided by the magnetic field shielding cylindrical support 128, and the second magnetic field shielding outer cylinder 40-5-2 is provided by the magnetic field shielding cylindrical support 120, respectively. Fixed to the floor 117. The cryostat 50-1 on the side where the SQUID magnetometer 57 is two-dimensionally arranged is fixed to the gantry 124 so as to be movable. The positional relationship between the examination site of the patient 36 sitting on the chair 122 movable in the x and y directions and the surface of the cryostat 50-1 on the side where the SQUID magnetometer 57 is arranged, and the height of the cryostat 50-1 After the position is adjusted, the cryostat 50-1 is fixed by the cryostat position fixing lock 126.
[0109]
The height of the second portion 40-6 of the magnetic field shielding device is set higher than the height of the first portion 40-5 of the magnetic field shielding device to rotate the second portion 40-6 of the magnetic field shielding device. Simplify the structure. The second part 40-6 of the magnetic field shielding apparatus has a circumference of about 200 degrees, and the first part 40-5 of the magnetic field shielding apparatus has a circumference part of 180 degrees, and each has a circumferential part of about 180 degrees. The configuration overlaps within a range of 10 degrees. That is, the first magnetic field shield inner cylinder 40-5-1 and the second magnetic field shield inner cylinder 40-6-1, and the second magnetic field shield outer cylinder 40-5-2 and the second magnetic field shield outer cylinder. 40-6-2 each forms a closed magnetic shielding device when overlapping at a range of about 10 degrees at both ends parallel to the central axis of the magnetic shielding device, and overlaps at a range of about 180 degrees. , Forming an open magnetic field shielding device.
[0110]
In the closed state, the overlapping portion is made sufficiently large to enhance the magnetic field shielding effect, and the component perpendicular to the central axis of the magnetic field shielding device 40 of the external magnetic field is converted into the innermost magnetic field shielding cylinders 40-5-1, 40-6. -1 can be shielded with a high magnetic field shielding rate. In the space where the external magnetic field is shielded with a high magnetic field shielding rate, the x-direction component of the biomagnetic field from the examination site can be detected with high sensitivity.
[0111]
Rotating the second part 40-6 of the magnetic field shielding device to create an open space, and with the patient 36 sitting on the chair 122, the doctor determines the positional relationship between the examination site of the patient 36 and the outer surface of the cryostat 50-1. Adjust.
[0112]
The central axes of the magnetic field shielding cylinders 60 constituting the magnetic field shielding device used in the sixth embodiment are arranged coaxially, and each magnetic field shielding cylinder is divided by a plane parallel to the central axis. Each magnetic field shielding cylinder is arranged vertically. In the magnetic field shielding apparatus used in the sixth embodiment, the patient 36 can easily enter the magnetic field shielding apparatus, and the examination site can be positioned efficiently. The magnetic field shielding device used in Example 6 is small, and the installation area of the biomagnetic field measuring device can be small.
[0113]
Note that the height of the cryostat 50-1 is fixed, and instead of the x and y direction moving device, the x, y and z directions for controlling the x, y and z direction movement of the chair 122 on which the examination object 36 sits are controlled. It goes without saying that the moving device can be used to align the surface of the cryostat 50-1 on the side where the SQUID magnetometer 57 is arranged and the surface of the inspection site of the inspection object 36.
(Example 7)
FIG. 16 is a cross-sectional view of a biomagnetic field measurement apparatus using the magnetic field shielding apparatus shown in FIGS. In the biomagnetic field measurement apparatus according to the seventh embodiment, the magnetic field shielding apparatus illustrated in FIGS. Other configurations are the same as those in the sixth embodiment.
(Example 8)
FIG. 17 is a perspective view showing a configuration example of the biomagnetic field measurement apparatus according to the eighth embodiment of the present invention. 18 is a cross-sectional view taken along a plane passing through the center of the measurement visual field of the biomagnetic field measurement apparatus shown in FIG.
[0114]
Hereinafter, the difference from the first embodiment will be mainly described. The magnetic shielding device 40-7 includes a magnetic shielding inner cylinder 40-7-1 and a magnetic shielding outer cylinder 40-7-2. The magnetic shielding device 40-7 is a magnetic shielding device support fixed to the floor 117. 130.
[0115]
In the eighth embodiment, since a flat SQUID magnetometer in which a detection coil for detecting a magnetic field is a thin film is used, a small cryostat can be used. In the eighth embodiment, the configuration of the magnetic field shielding device 40 described in the first embodiment does not form the third opening 43 into which the cryostat 50 is inserted, and the cryostat 50-2 in which the SQUID magnetometer is two-dimensionally arranged at the bottom. Is placed inside the magnetic shielding inner cylinder 40-7-1. The cryostat 50-2 is held by a cryostat holding plate 132, and the cryostat holding plate 132 is held by a fixed base 131 of a cryostat holding plate fixed to the floor 117.
[0116]
The bed on which the bed 20, the x and y direction moving devices 21 are mounted and the support base 22 of the moving device are arranged inside the magnetic field shielding inner cylinder 40-7-1 through the spacer 140-2. In the example shown in FIG. 18, the filler 70-3 is filled in the lower half, but it goes without saying that the upper half may also be filled.
[0117]
In the eighth embodiment, since the third opening described in the first embodiment is not formed, the component perpendicular to the central axis of the magnetic field shielding device 40 of the external magnetic field is set inside the innermost magnetic field shielding cylinder 40-7-1. Thus, it is possible to shield with a higher magnetic field shielding rate than the magnetic field shielding device shown in the first embodiment. The z-direction component of the biomagnetic field from the examination site can be detected with high sensitivity in a space where the external magnetic field is shielded with a higher magnetic field shielding rate.
[0118]
The patient placed on the bed 20 passes the second opening 42 to the inside of the magnetic shielding inner cylinder 40-7-1, and more preferably, the foot portion first passes through the lower portion of the cryostat 50-2. , Inserted so that the chest reaches the bottom of the cryostat and minimizes the feeling of pressure. Of course, as shown in FIG. 18, it may be carried into the inside of the magnetic field shield inner cylinder 40-7-1 from the head. The doctor determines the positional relationship between the examination site of the patient 36 and the bottom surface of the cryostat 50-2 by moving the height direction moving device (in the x and y direction moving device 21 of the bed 20 and the fixed base 131 of the cryostat holding plate ( After adjustment using the position adjustment device, the biomagnetic field from the examination site is measured.
[0119]
It goes without saying that the x, y, z direction moving device of the bed 20 can be used in place of the x and y direction moving device 21 as the position where the height of the cryostat 50-2 is fixed as in the first embodiment. Yes. Furthermore, it goes without saying that the fourth opening may be omitted as in the first embodiment.
Example 9
FIG. 19 is a diagram showing an example of a magnetic field waveform measured by the biomagnetic field measurement apparatus shown in Example 1 of the present invention. FIG. 19 shows a magnetic field generated from the heart of a healthy person detected using a total of four channels of SQUID magnetometers arranged at the apexes of the square at the bottom of the cryostat, and shows a one-channel magnetic field waveform. In FIG. 19, the horizontal axis represents time (sec), and the vertical axis represents the differential value (pT / m) of the detected magnetic field.
[0120]
The configuration of the magnetic shielding apparatus 40 used when obtaining the measurement result of Example 8 is as follows. The magnetic field shielding device used is composed of first, second, and third magnetic field shielding cylinders 60 that are coaxially arranged from the inside to the outside, and has a high permeability on the outside of the high permeability sheet support cylinder 80. A high permeability sheet layer 82 was formed from the sheet 23. The magnetic field shielding device used does not have a fourth opening. The third opening was circular with a radius of 30 cm in order to insert a cryostat with a circular cross-section in which a 4-channel SQUID magnetometer was placed.
[0121]
An aluminum hollow cylinder having an inner radius of 80 cm, 90 cm, and 100 cm, a thickness of 0.5 mm, and a length of 200 cm was used as the first magnetic field shielding cylinder, the second magnetic field shielding cylinder, and the third magnetic field shielding cylinder, respectively. The third opening was provided at the center in the length direction of each hollow cylinder.
[0122]
The high magnetic permeability sheet 23 used was a commercial product (Hitachi Metals, trade name Finemet). This high magnetic permeability sheet 23 is an Fe-Cu-Nb-Si-B system (high magnetic permeability material) having an ultrafine crystal structure with a grain boundary size of 100 nm or less and a maximum relative magnetic permeability of 50,000 or more ( Fe: 73.5%, Cu: 1%, Nb: 3%, Si: 13.5%, B: 9%) are used.
[0123]
The configuration of the high permeability sheet used is that the thickness of the magnetic material ribbon (high permeability material) 25 is about 20 μm, the thickness of the holding sheets 26-1 and 26-2 is 30 μm, and the total thickness of the high permeability sheet 23 is 100 μm. . The high permeability sheet 23 having an area of 610 cm × 240 cm was overlapped and pasted on the outer peripheral surface of each aluminum hollow cylinder to form a high permeability sheet layer 82 having a thickness of about 1 mm.
[0124]
As shown in FIG. 2, the flexible high-permeability sheet 23 is formed so that the long side of each magnetic material ribbon 25 is each hollow cylinder so that the short side of the magnetic material ribbon 25 is substantially parallel to the central axis of each hollow cylinder. A plurality of layers of the high magnetic permeability sheet 23 are attached to the peripheral surface of each hollow cylinder by using an adhesive so that the central axis of each hollow cylinder is surrounded inward and substantially parallel to a plane perpendicular to the central axis of each hollow cylinder. Formed.
[0125]
By using a magnetic shielding device having a simple configuration, the component perpendicular to the central axis of the magnetic shielding device for external magnetic field (the central axes of the first, second, and third magnetic shielding cylinders) It was able to attenuate to -35 dB at the position of the central axis of one magnetic field shielding cylinder. That is, at the position of the central axis of the innermost first magnetic field shielding cylinder, the component of the external magnetic field in the direction perpendicular to the central axis of the magnetic field shielding device can be attenuated to -35 dB. As a result, the SQUID magnetometer can detect with high sensitivity the component in the z direction of the biomagnetic field generated from the test site of the living body placed inside the magnetic shielding apparatus.
[0126]
The magnetic field shielding rate of the magnetic field shielding device used is 1/56 at the position of the central axis of the magnetic field shielding device, and the magnetic field generated from the heart of an adult healthy person can be measured with an S / N ratio of 10 or more at the time of R wave output. found.
[0127]
A high permeability sheet 23 is affixed to the peripheral surface of each hollow cylinder so that the long side of the magnetic material ribbon 25 is parallel to the central axis of each hollow cylinder to form a plurality of layers of the high permeability sheet 23. When each magnetic field shielding cylinder is formed, the external magnetic field component perpendicular to the central axis of the magnetic field shielding device is attenuated to about -31 dB at the position of the central axis of the innermost first magnetic field shielding cylinder. did it.
[0128]
When the fourth opening is provided in the configurations of the first embodiment, the second embodiment, the third embodiment, the fourth embodiment, the fifth embodiment, and the eighth embodiment described above, the inner diameter of the innermost magnetic shielding cylinder is provided. Is about 1 m, the diameter of the fourth opening can be about 30 cm.
[0129]
In addition, in the configurations of Example 1, Example 2 and Example 8, when the test object (patient) is brought into the inner space of the innermost magnetic field shielding cylinder of the magnetic field shielding device, the foot part is first placed in the cryostat. Pass through the lower part, and finally make the chest reach the lower part of the cryostat so as to minimize the feeling of pressure.
[0130]
【The invention's effect】
According to the present invention, a high-permeability sheet having a high magnetic permeability can be realized by using a high-permeability sheet having a high permeability. Since the magnetic field shielding device of the present invention is light and small, load resistance is not particularly required at the installation location, and installation is possible if there is a small area, and a magnetic field shielding device, that is, a magnetic field measuring device is installed. There are no restrictions on the location.
[0131]
In the magnetic field measurement apparatus of the present invention, a magnetic field distribution map in which a peak pattern appears just above the current source can be obtained only from the measurement of the normal component of the magnetic field without measuring the tangential component in the two directions of the magnetic field. As a result, since the position of a plurality of current sources in the living subject can be directly read, data useful for diagnosis of diseases related to the heart of adults and fetuses can be obtained when the subject to be examined is a living body. The magnetic field measurement apparatus of the present invention can measure and display the magnetic field from the inspection object in a short time.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration example of a high permeability sheet having a high permeability used in each embodiment of the present invention.
FIG. 2 is a perspective view for explaining an arrangement example of a high permeability sheet on a hollow cylinder constituting the magnetic field shielding device in each embodiment of the present invention.
FIG. 3 is a cross-sectional view for explaining an arrangement example of a high permeability sheet on a hollow cylinder constituting the magnetic field shielding device in each embodiment of the present invention.
FIG. 4 is a perspective view illustrating a configuration example of a biomagnetic field measurement apparatus according to Embodiment 1 of the present invention.
5 is a perspective view of the magnetic field shielding device shown in FIG. 4. FIG.
6 is a cross-sectional view taken along a plane passing through the center of the measurement field of view of the biomagnetic field measurement apparatus shown in FIG.
FIG. 7 is a perspective view showing a configuration example of a biomagnetic field measurement apparatus according to Embodiment 2 of the present invention.
8 is a perspective view of the magnetic shielding apparatus shown in FIG.
9 is a cross-sectional view taken along a plane passing through the center of the measurement field of view of the biomagnetic field measurement apparatus shown in FIG.
FIG. 10 is a perspective view showing a configuration example of a biomagnetic field measurement apparatus according to Embodiment 3 of the present invention.
11 is a perspective view of the magnetic field shielding device shown in FIG.
12 is a cross-sectional view for explaining taking in and out of a test object (patient) to and from the biomagnetic field measurement apparatus shown in FIG. 7;
FIG. 13 is a perspective view including a partially broken portion showing an example of a medical examination vehicle that is an embodiment of the fifth embodiment of the present invention and in which the biomagnetic field measurement device according to the third or fourth embodiment is mounted on an automobile.
FIG. 14 is a perspective view showing a configuration example of a magnetic shielding apparatus used in a biomagnetic field measurement apparatus according to Embodiment 6 of the present invention.
15 is a cross-sectional view taken along a plane passing through the center of the measurement field of view of the biomagnetic field measurement apparatus using the magnetic field shielding apparatus shown in FIG.
16 is a cross-sectional view taken along a plane passing through the center of the measurement visual field of the biomagnetic field measurement apparatus using the magnetic field shielding apparatus shown in FIG. 14 according to the seventh embodiment of the present invention.
FIG. 17 is a perspective view illustrating a configuration example of a biomagnetic field measurement apparatus according to an eighth embodiment of the present invention.
18 is a cross-sectional view taken along a plane passing through the center of the measurement visual field of the biomagnetic field measurement apparatus shown in FIG.
FIG. 19 is a diagram illustrating an example of a magnetic field waveform measured by the biomagnetic field measurement apparatus according to the first embodiment of the present invention.
[Explanation of symbols]
20, 20-1 ... bed, 21 ... x and y direction moving device, or x, y, z direction moving device, 21 '... x, y, z direction moving device, 22 ... bed and moving device support base, 23 ... high permeability sheet, 24 ... flexible resin or adhesive, 25 ... magnetic material ribbon, 26-1, 26-2 ... holding sheet, 29-1, 29-2, 29-3, 29-4 ... Wheel, 29'-1, 29'-2, 29'-3, 29'-4 ... Wheel, 30-1 ... Magnetic field shielding device / gantry support, 30-2 ... Gantry, 31 ... Gantry height control device , 32 ... Gantry height control box, 35 ... Examiner (doctor), 36 ... Examination object (patient), 40 ... Magnetic field shielding device, 40-1 ... First part of magnetic field shielding device, 40-1-1 ... 1st magnetic field shielding inner cylinder, 40-1-2 ... 1st magnetic field shielding outer cylinder, 40-2 ... Magnetic field shielding apparatus , A second magnetic field shielding inner cylinder, 40-2-2 a second magnetic field shielding outer cylinder, 40-3, a first part of the magnetic field shielding device, 40-3. -1 ... first magnetic field shielding inner cylinder, 40-3-2 ... second magnetic field shielding outer cylinder, 40-4 ... second part of magnetic field shielding device, 40-4-1 ... second magnetic field shielding inner side Cylinder, 40-4-2 ... second magnetic field shielding outer cylinder, 40-5 ... first part of magnetic field shielding device, 40-5-1 ... first magnetic field shielding inner cylinder, 40-5-2 ... first 2 magnetic shielding outer cylinder, 40-6 ... second part of magnetic shielding device, 40-6-1 ... second magnetic shielding inner cylinder, 40-6-2 ... second magnetic shielding outer cylinder, 40- 7 ... Magnetic field shielding device, 40-7-1 ... Magnetic field shielding inner cylinder, 40-7-2 ... Magnetic field shielding outer cylinder, 41 ... First opening, 42 ... Second opening, 43 3rd opening, 44 ... 4th opening, 50, 50-1, 50-2 ... Cryostat, 51 ... Data collection / sensor control line, 52 ... Data collection processing / sensor control device, 53 ... Display device, 54 ... refrigerant supply line or cooling transmission line, 55 ... refrigerant supply apparatus or cooling device, 56 ... refrigerant, 57 ... SQUID magnetometer, 60 ... magnetic field shielding cylinder, 60-1 ... first magnetic field shielding cylinder, 60-2 ... first 2 magnetic shielding cylinders, 70, 70-1, 70-2, 70-3 ... filler, 80 ... high permeability sheet supporting cylinder, 82 ... high permeability sheet layer, 90-1, 90-2 ... rail, DESCRIPTION OF SYMBOLS 91 ... Wheel, 92 ... Magnetic field shielding apparatus support stand, 100, 100-1 ... Wheel, 101 ... Connection part, 103 ... Bed moving stand, 105 ... Guide, 110 ... Floor in vehicle, 111 ... Anti-vibration stand, 112 ... Anchor 115 ... Coupling plate 116 ... Move Upper coupling part, 117 ... floor, 117-1 ... inclined floor, 118 ... wheel, 119 ... moving guide groove, 120, 128 ... magnetic field shielding cylindrical support, 122 ... chair, 124 ... gantry, 126 ... cryostat position Fixed lock, 130 ... magnetic field shielding device support, 131 ... cryostat holding plate fixing base, 132 ... cryostat holding plate, 140-1, 140-2 ... spacer, 150-1, 150-2 ... coupling plate.

Claims

The first and second cylindrical members are divided into two in the circumferential direction by the first and second cylindrical members which are formed of a material having high permeability and having a circumferential portion with a first and a second predetermined angle, and one shaft is concentrically disposed. The first cylindrical member and the second cylindrical member overlap each other at a third predetermined angle at both ends parallel to the one axis by rotation of the second cylindrical member around the one axis. A magnetic field shielding device comprising a closed state in a circumferential direction and shielding a component of a foreign magnetic field in a direction perpendicular to the one axis.

2. The magnetic field shielding apparatus according to claim 1, wherein the one axis is an axis horizontal to the floor, and has means for fixing the first cylindrical member to the floor surface perpendicular to the one axis. Magnetic field shielding device.

2. The magnetic field shielding apparatus according to claim 1, wherein the one axis is an axis perpendicular to the floor, and has means for fixing the first cylindrical member to the floor surface substantially parallel to the one axis. Magnetic field shielding device.

The first and second cylindrical members are divided into two in the circumferential direction by the first and second cylindrical members which are formed of a material having high permeability and having a circumferential portion with a first and a second predetermined angle, and one shaft is concentrically disposed. The first cylindrical member and the second cylindrical member overlap each other at a third predetermined angle at both ends parallel to the one axis by rotation of the second cylindrical member around the one axis. A magnetic field shielding device configured to shield a component in a direction perpendicular to the one axis of the external magnetic field, and a body axis direction within the magnetic field shielding device about the one axis. Means for holding the living body in parallel; and a cryostat arranged inside the magnetic field shielding device and holding a plurality of SQUID magnetometers at a low temperature, and the first cylindrical member by rotation of the second cylindrical member And the second cylindrical member overlap at the third predetermined angle and the circumferential direction In the closed state, the plurality of SQUID fluxmeter biomagnetic field measuring apparatus characterized by detecting the component perpendicular to one axis of the magnetic field emanating from the living body.

5. The biomagnetic field measurement apparatus according to claim 4, wherein the one axis is an axis parallel to the floor, and has means for fixing the first cylindrical member to the floor surface perpendicular to the one axis. A biomagnetic field measuring apparatus.

5. The biomagnetic field measurement apparatus according to claim 4, wherein the one axis is an axis perpendicular to the floor, and has means for fixing the first cylindrical member to the floor surface substantially parallel to the one axis. A biomagnetic field measuring device as a feature.