JPS6117053A - Nuclear magnetic resonance image sensor - Google Patents
Nuclear magnetic resonance image sensorInfo
- Publication number
- JPS6117053A JPS6117053A JP59137799A JP13779984A JPS6117053A JP S6117053 A JPS6117053 A JP S6117053A JP 59137799 A JP59137799 A JP 59137799A JP 13779984 A JP13779984 A JP 13779984A JP S6117053 A JPS6117053 A JP S6117053A
- Authority
- JP
- Japan
- Prior art keywords
- magnetic field
- static magnetic
- static
- yoke
- auxiliary coil
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/38—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
- G01R33/387—Compensation of inhomogeneities
- G01R33/3875—Compensation of inhomogeneities using correction coil assemblies, e.g. active shimming
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/24—Arrangements or instruments for measuring magnetic variables involving magnetic resonance for measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/246—Spatial mapping of the RF magnetic field B1
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/38—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
- G01R33/3806—Open magnet assemblies for improved access to the sample, e.g. C-type or U-type magnets
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
- G01R33/28—Details of apparatus provided for in groups G01R33/44 - G01R33/64
- G01R33/38—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field
- G01R33/383—Systems for generation, homogenisation or stabilisation of the main or gradient magnetic field using permanent magnets
Landscapes
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Magnetic Resonance Imaging Apparatus (AREA)
Abstract
Description
【発明の詳細な説明】
ビ） 産業上の利用分野
本発明は、核磁気共鳴撮像装置（以下、ＮＭＲ−ＯＴと
称す）に関する。DETAILED DESCRIPTION OF THE INVENTION B) Industrial Application Field The present invention relates to a nuclear magnetic resonance imaging apparatus (hereinafter referred to as NMR-OT).
初 従来の技術
Ｎ−ＭＲ−０−Ｔにおいて、均一度の高い静磁界を形成
することが必要となる。こうした静磁界を形成する静磁
界発生手段には、一般に１日本臨床４１巻７号（７，１
９８５）のＰ２５４〜Ｐ２５７に見られるように、常伝
導磁石、超伝導磁石もしくは永久磁石が使用されるが、
いずれめ場合においても、磁石だけによって約１ｏｐｐ
ｍの均一度を有した静磁界を形成することは不可能であ
る。First, in the conventional technique N-MR-0-T, it is necessary to form a highly uniform static magnetic field. The static magnetic field generating means for forming such a static magnetic field generally includes 1 Japan Clinical Practice Vol. 41 No. 7 (7, 1
985), normal conducting magnets, superconducting magnets or permanent magnets are used,
In either case, approximately 1 opp is generated by the magnet alone.
It is not possible to create a static magnetic field with a uniformity of m.
従って１日本化学会編、°磁気“、新実験化学講座３．
基礎技術２．丸善（１９７６’）のＰ５０〜３２に見ら
れるように、静磁界の均一性を上げるための補助コイル
が用いられる。Therefore, 1. edited by the Chemical Society of Japan, °Magnetism, New Experimental Chemistry Course 3.
Basic technology 2. As seen in P50-32 of Maruzen (1976'), an auxiliary coil is used to improve the uniformity of the static magnetic field.
今、静磁界の磁場方向ｔｌ−ｚ軸とすると、磁場の空間
分布の２成分Ｂｚは。Now, assuming that the magnetic field direction of the static magnetic field is the tl-z axis, the two components Bz of the spatial distribution of the magnetic field are.
Ｂ ＺＷＡ６ 。＋Ａ、 。Ｚ ＋Ａ１１Ｘ＋Ｂ□、
Ｙ＋Ａ、。BZWA6. +A, . Z +A11X+B□,
Y+A.
（２Ｚ”−Ｘ”−Ｙ” ）／２＋！ＩＡ、１ＺＸ＋ｌ、
１ＺＹ＋！ｔＡ、、（Ｘ”−Ｙ”）＋６Ｂ＊、ＸＹＥ＝
−” （１１で近似される。なお Ａ ｍ
ｎ、 Ｂ、ｍｎは定数である。(2Z"-X"-Y")/2+!IA, 1ZX+l,
1ZY+! tA,, (X"-Y")+6B*,XYE=
−” (approximated by 11. Note that A m
n, B, mn are constants.
ここで、（１）式において、定数へ。のみが残るように
、上記補助コイルによって（１）式の各項の磁場成分を
打ち消す磁場を形成すればよい。例えば、′第６図に示
すように、ＺＭを中心とし、かつＸＹ面に対称に２つの
円形コイル（ｊｌ（１）を配置し、コイル■■に夫々相
反する方向（図中、矢印方向）の電流Ｉｉ印加すると、
これらコイル■圓の発生する磁場ＤＺは。Here, in equation (1), to the constant. What is necessary is to form a magnetic field using the auxiliary coil to cancel out the magnetic field components of each term in equation (1) so that only the magnetic field components remain. For example, as shown in Fig. 6, two circular coils (jl(1) are arranged centered on ZM and symmetrical in the XY plane, and the coils When a current Ii of is applied,
The magnetic field DZ generated by these coil circles is:
ｂ ｚ −ａ Ｘ Ｚ −”−
＝ （２１となる（！Ｌは定数）。従って、 Ａ１．＋
ａＩ＝−０となるように、電流工を決定することによっ
て、（１）式における八□６Ｚの成分を打ち消すことが
できる。b z -a X Z -”-
= (21 (!L is a constant). Therefore, A1.+
By determining the current so that aI=-0, the component of 8□6Z in equation (1) can be canceled.
このようにして、（１）式のＡｏ。以外の各項に対応し
て、それらを打ち消すような磁場を形成する補助コイル
を静磁界中に配し、均一度の高い静磁界を形成すること
ができる。In this way, Ao in equation (1). By disposing an auxiliary coil in the static magnetic field to form a magnetic field that cancels out the other terms, it is possible to form a highly uniform static magnetic field.
ところで、このような静磁界発生手段において磁性材料
の存在が大きな問題となる。即ち、常伝導磁石もしくは
超伝導磁石を用いた静磁界発生手段においては、漏洩磁
束が大きく、この漏洩磁束の領域内に磁性材料が存在す
ると、常伝導磁石もしくは超伝導磁石が形成する磁場分
布は歪み、（１）式の各定数が変化する。この変化度合
いは、上記磁性材料の存°在位置及び量等に依存し、従
って、補正コイルにて形成すべき磁場を容易に決定する
ことは不可能となる。By the way, the presence of a magnetic material in such a static magnetic field generating means poses a big problem. That is, in a static magnetic field generation means using a normal conducting magnet or a superconducting magnet, the leakage magnetic flux is large, and if a magnetic material exists in the region of this leakage magnetic flux, the magnetic field distribution formed by the normal conducting magnet or superconducting magnet will be distortion, and each constant in equation (1) changes. The degree of this change depends on the location and amount of the magnetic material, and therefore it is impossible to easily determine the magnetic field to be formed by the correction coil.
一方、永久磁石を用いた静磁界発生手段においては、一
対の永久磁石を磁気的に結合する磁気ヨークにより、は
ぼ密閉された空間を形成し、この９間内に静磁界を形成
することによって、外部への漏洩磁束を小さく１１周辺
の磁性材料による悪影響を防止している。On the other hand, in a static magnetic field generating means using permanent magnets, a nearly sealed space is formed by a magnetic yoke that magnetically couples a pair of permanent magnets, and a static magnetic field is generated within this space. , the leakage magnetic flux to the outside is reduced to prevent the negative influence of the magnetic material around 11.
しかし乍ら、斯る場合、補助コイルに近接して多量の磁
性材料、即ち磁気ヨークが存在することとな夛、補助コ
イルが形成する磁場が歪められる。However, in such a case, due to the presence of a large amount of magnetic material, ie, a magnetic yoke, in close proximity to the auxiliary coil, the magnetic field created by the auxiliary coil is distorted.
従って、（２）式に示すように、（１）式の各項を単独
で打ち消すような磁場を形成する補助コイルを作成する
ことは困難となる。Therefore, as shown in equation (2), it is difficult to create an auxiliary coil that forms a magnetic field that cancels out each term in equation (1) by itself.
以上のように、上記し、た各磁石を使用する静磁界発生
手段には、夫々一長一短があるものの、常伝導磁石を使
用したものにおいては、消費電力が大きく、更に大電流
を印加するために発熱を生じ、バ゛
これによる温度上昇を防止するための冷却装置必す
要となり、装置が大型となる。また、超伝導磁石を使用
したものにおいては、超伝導状態を保持するために液体
ヘリウム、液体窒素を定期的に補充しなければならず、
維持することに問題がある。As mentioned above, the static magnetic field generating means using each of the magnets mentioned above have their own advantages and disadvantages, but those using normal conducting magnets consume a lot of power, and it is difficult to apply a large current. Heat is generated, and a cooling device is required to prevent the temperature from rising due to heat generation, which increases the size of the device. Additionally, in those using superconducting magnets, liquid helium or liquid nitrogen must be periodically replenished to maintain the superconducting state.
There are problems with maintaining it.
従って、これらの各問題点を解消、即ち、冷却へ
界発生手段である。更にこれは、漏洩磁束が小さいため
、周囲環境に影響されることなく均一度の高い静磁界を
保持することができる。Therefore, each of these problems can be solved by means of generating a cooling field. Furthermore, since leakage magnetic flux is small, a highly uniform static magnetic field can be maintained without being affected by the surrounding environment.
（ハ）発明が解決しようとする問題点
既述の如く、永久磁石による静磁界発生手段は、常伝導
磁石もしくは超伝導磁石による静磁界発生手段にはない
優れた利点を有しているが、補助コイルが形成する磁場
は、磁気ヨークにて歪められて単に補助コイルが単独で
形成する磁場だけを考慮することは無意味なものとなり
、従って、（１）式の定数項以外の項を打ち消すように
補助コイルを設定することは困難となる。(c) Problems to be Solved by the Invention As already mentioned, static magnetic field generating means using permanent magnets has excellent advantages that static magnetic field generating means using normal conducting magnets or superconducting magnets do not have. The magnetic field formed by the auxiliary coil is distorted by the magnetic yoke, and it becomes meaningless to consider only the magnetic field formed by the auxiliary coil alone. Therefore, terms other than the constant term in equation (1) are canceled out. This makes it difficult to set up auxiliary coils.
に）問題点を解決するための手段
本発明は、核磁気共鳴撮像装置において、永久磁石を備
えた静磁界発生手段は、上記一対の永久磁石の夫々に近
接する配置で、上記静磁界の一様性を補正するための複
数の補助コイルを具備し。B.) Means for Solving the Problems The present invention provides a nuclear magnetic resonance imaging apparatus in which a static magnetic field generating means including a permanent magnet is arranged close to each of the pair of permanent magnets to generate one of the static magnetic fields. Equipped with multiple auxiliary coils to correct the characteristics.
該補助コイルヘの印加電流は、上記永久磁石の静磁界分
布及び補助コイルが形成する磁場への上記磁気ヨークの
影響を打ち消すように決定されることを特徴とする。The current applied to the auxiliary coil is determined so as to cancel the influence of the magnetic yoke on the static magnetic field distribution of the permanent magnet and the magnetic field formed by the auxiliary coil.
（ホ）作 用 本発明は、磁気ヨークによる影響を考慮して。(e) Production The present invention takes into account the influence of the magnetic yoke.
静磁界を均一に補正するための補助コイルヘの印加電流
を決定するものであるから、静磁界発生手段が発生する
静磁界は、高均一度のものとなる。Since the current to be applied to the auxiliary coil for uniformly correcting the static magnetic field is determined, the static magnetic field generated by the static magnetic field generating means has a high degree of uniformity.
（へ）実施例
第１図（＆）及び（′ｂ）は、ＮＭＲ−ＯＴにおける静
磁界発生手段を夫々一部破断して示す部分上面図及び側
面図である。(f) Embodiment FIGS. 1 (&) and ('b) are a partially cutaway top view and a side view, respectively, of a static magnetic field generating means in an NMR-OT.
同図に示す静磁界発生手段（１）において、 （２１（
２）は希土類磁石材料から成る一対の円板状永久磁石。In the static magnetic field generating means (1) shown in the figure, (21(
2) is a pair of disc-shaped permanent magnets made of rare earth magnet material.
＜３）（４）は該永久磁石の各々の一面に接して配され
る磁社材料から成る円板状の上部ヨーク及び下部ヨーク
、（５）は該上部ヨーク及び下部ヨークと電磁気的に接
続される磁１匹材料から成る円筒状のサイドヨークで、
この開口を密閉するように上部ヨーク（３）及び下部ヨ
ーク（４）が配されることによって、これらの各ヨーク
にて磁気回路を構成し、一対の永久磁石（２）の対向間
に静磁界が形成される。また、。<3) (4) is a disc-shaped upper yoke and a lower yoke made of magnetic material arranged in contact with one surface of each of the permanent magnets, and (5) is electromagnetically connected to the upper yoke and the lower yoke. A cylindrical side yoke made of magnetic material,
By arranging the upper yoke (3) and the lower yoke (4) so as to seal this opening, a magnetic circuit is formed by each of these yokes, and a static magnetic field is generated between the pair of facing permanent magnets (2). is formed. Also,.
サイドヨーク（５）は、上記静磁界中への被測定物の設
置用九対向配置で設けられた一対の円形開口（６）及び
採光用の複数の小孔（７）ｔｌ−有する。（８０８）は
永久磁石（２）＋２１の各々の他面に対向配置で設けら
れ、上記静磁界の均一度を向上させる一対の？−ルピー
ス、（９）はサイドヨーク（５）の上部内面に突出して
設けられ、上部ヨーク（３）を支持する受座リング、σ
〔（１Ｇは一端が各ぜ−ルビース（８）の側面に接して
配され１例えば上部ヨーク（３）及び下部ヨーク（４）
にねじ止めされる断面り字状のサイドリングで、各永久
磁石（２）は各サイドリンクα〔により位置決めされる
と共に、上部ヨーク（３）もしくは下部ヨーク（４）と
各サイドリング（１〔とによって挟持固定される。The side yoke (5) has a pair of circular openings (6) arranged opposite each other for installing the object to be measured in the static magnetic field, and a plurality of small holes (7) for letting in light. (808) are provided on the other surface of each of the permanent magnets (2)+21 in opposing arrangement, and are a pair of magnets (808) to improve the uniformity of the static magnetic field. - piece (9) is a seat ring, σ, which is provided protruding from the upper inner surface of the side yoke (5) and supports the upper yoke (3);
[(1G is arranged so that one end is in contact with the side surface of each of the beads (8) 1, for example, the upper yoke (3) and the lower yoke (4)
Each permanent magnet (2) is positioned by each side link α [, and the upper yoke (3) or lower yoke (4) and each side ring (1 [ It is clamped and fixed by.
また、 ＋１１１（Ｉｌｌは本発明の特徴である一対の
補助コイル体であり、ポールピース（８）（８）の夫々
の表面に 。In addition, +111 (Ill is a pair of auxiliary coil bodies that are a feature of the present invention, and are located on the respective surfaces of the pole pieces (8) (8).
対向配置で設けられている。They are placed in a facing arrangement.
＄２図は、補助コイル体σＤの上面図を示し、（１ｚは
非磁性体からなる樹脂板、任３０・・・は該樹脂板の一
表面に設けられた溝であり、これら溝に活って補助コイ
ルとなる銅線が夫々巻回される。そしてこれら各補助コ
イルに電流を印加することによって永久磁石（２１（２
１が形成した静磁界を補正する磁場が発生する。Figure 2 shows a top view of the auxiliary coil body σD, (1z is a resin plate made of a non-magnetic material, numerals 30... are grooves provided on one surface of the resin plate, and these grooves have active parts. Copper wires serving as auxiliary coils are wound respectively. By applying current to each of these auxiliary coils, a permanent magnet (21 (2)
A magnetic field is generated that corrects the static magnetic field formed by 1.
ところで、本実施例の静磁界発生手段（１）において、
補助゛コイル体（ｉｌｌ（１１１の近傍には磁性体から
なるサイドヨーク（５）が在社するため、補助コイル体
計υαυが形成する磁場はサイドヨーク（５）にて歪め
られる。従って、補助コイル体ｔｉｌｌ（１１１にて磁
場を形成する場合、斯るサイドヨーク（５）による歪み
を考慮しなければならない。By the way, in the static magnetic field generating means (1) of this embodiment,
Since there is a side yoke (5) made of a magnetic material near the auxiliary coil body (111), the magnetic field formed by the auxiliary coil body υαυ is distorted by the side yoke (5). When forming a magnetic field with the coil body (111), distortion caused by the side yoke (5) must be taken into account.
即ち、永久磁石（２＋ （２）のみが形成する静磁界Ｂ
ｚ１は既述の（１）式にて近似できる。また、補助コイ
ル 。That is, the static magnetic field B formed only by the permanent magnet (2+ (2)
z1 can be approximated by the above-mentioned equation (1). Also, auxiliary coil.
体Ｑｌｌ（ｌυのｊ番の補助コイルに電流Ｉｊを流した
時の磁場ｔＢｚ（１ｊ） とし、このｊ番の補助コイ
ルによる磁場（ＢＥ（Ｉｊ）−Ｂｚｌ）＝ΔＢＺ（Ｉｊ
）は、（１）式と同様に近似する必要があり、この時の
係数を０，９．（Ｉｊ）、Ｄ番□（工ｊ）とする。今。Let the magnetic field tBz (1j) when a current Ij flows through the j-th auxiliary coil of the body Qll (lυ) be given, and the magnetic field due to this j-th auxiliary coil (BE (Ij) - Bzl) = ΔBZ (Ij
) needs to be approximated in the same way as equation (1), and the coefficients at this time are set to 0, 9, . (Ij), D number □ (engineering j). now.
ＢＺＩは定数項以外の項を８つ有することから。This is because BZI has eight terms other than the constant term.
補助コイル体Ｑ■Ｄは８種類の補助コイルを必要とする
。そして、との静磁界発生手段（１）における静磁界Ｂ
Ｚ［ｌは。Auxiliary coil body QD requires eight types of auxiliary coils. And the static magnetic field B in the static magnetic field generating means (1) with
Z[l is.
＋ｑ４１ＺＸ＋３Ｂ、、ＺＹ＋３Ａ、（ｘ’−ｙｊ）＋
６もＸＹｊ コ ｊ
＋’ｘａ（Ｉｊ）（２Ｚ”−Ｘ”−Ｙ” ｌ／２＋５Ｑ
ｔ（Ｉｊ）ＺＸ＋５Ｑｓ（Ｉｊ）Ｚ”一
”’ Ｑｌ ｍ （工ｊ） （Ｘ”−Ｙ” ）＋ ６Ｄ
ｌｓ （Ｉｊ）ＸＹ ）ＱＯ−や）
となる。+q41ZX+3B,,ZY+3A,(x'-yj)+
6 is also XYj Ko j +'xa (Ij) (2Z"-X"-Y" l/2+5Q
t(Ij)ZX+5Qs(Ij)Z"1"' Ql m (工j) (X"-Y")+6D
ls (Ij)XY)QO-ya).
ここで、均一な静磁界を得るためには、定数項以外の項
が全て０になることが必要となる。従って、
が成シ立つように、補助コイル体ａυＩの各補助コイル
に印加する電流を決定すればよい。ここで。Here, in order to obtain a uniform static magnetic field, it is necessary that all terms other than the constant term become 0. Therefore, the current to be applied to each auxiliary coil of the auxiliary coil body aυI may be determined so that the following holds true. here.
各係数Ｏｋ％（Ｉｊ）及びＤｋメ（Ｉ ｊ、 ）は、補
助コイル体（１１３ｆｉｌｌの各補助コイルを流れる電
流ｒｊに比例すｊ ｊ
るものであり、 Ｏｘ ７ （Ｉ ｊ ）＝Ｃｋｌ
Ｉ ｊ、 Ｄｋ！ （工ｊ）ｍａ ｊ Ｉｊ（Ｏｊ及び
ｄｋ％は定数）となる。Each coefficient Ok% (Ij) and Dk(Ij, ) are proportional to the current rj flowing through each auxiliary coil of the auxiliary coil body (113fill), and Ox7(Ij)=Ckl
I j, Dk! (Work j) ma j Ij (Oj and dk% are constants).
ＩＲｋＩ！
従って、（４）式は、
の行列式で表わすことができる。ここで、８行８列の行
列をＣ，電流の列ベクトルをＨ１係数の列ベクトルｅＡ
とすると、ｒｒ＝−ｃ−’Ａにより、補助コイル体０ｎ
（ｌυの各補助コイルに流すべき電流１ｊの値を決定す
ることができる。IRkI! Therefore, equation (4) can be expressed by the determinant of. Here, C is the matrix of 8 rows and 8 columns, and the column vector of the current is the column vector of H1 coefficient eA.
Then, due to rr=-c-'A, the auxiliary coil body 0n
(The value of the current 1j to be passed through each auxiliary coil of lυ can be determined.
このようにして７静磁界発生手段（１）は、均一度の高
い静磁界を形成することができる。そして。In this way, the 7 static magnetic field generating means (1) can generate a highly uniform static magnetic field. and.
この静磁界発生手段（１）は漏洩磁束が非常に小さいの
で１周囲に影響されることなく、均一度の高い静磁界を
保持することができる。Since this static magnetic field generating means (1) has a very small leakage magnetic flux, it is possible to maintain a highly uniform static magnetic field without being influenced by the surroundings.
ところで、ＮＭＲ−ＯＴにおいて、被測定物の断層撮像
を得んとする場合、静磁界発生手段（１）の静磁界内に
、夫々Ｘ、Ｙ及び２軸方向において傾斜している勾配磁
界が必要である。そこで、これら各勾配磁界を形成する
手段として、補助コイル体ｎｕｌｌ）ｌに設けられてい
る補助コイルの中で、ｘ。By the way, in NMR-OT, when trying to obtain a tomographic image of the object to be measured, gradient magnetic fields that are inclined in the X, Y and two axis directions are required in the static magnetic field of the static magnetic field generating means (1). It is. Therefore, as means for forming each of these gradient magnetic fields, among the auxiliary coils provided in the auxiliary coil body, x.
Ｙ及びＺ軸の項を補正する補助コイルを使用し。Use auxiliary coils to correct the Y and Z axis terms.
その他の項を補正する補助コイルは、Ｘ、Ｙ及び２０項
の係数が十分に小さくなるようにする。この場合、（５
）式は。The auxiliary coil that corrects the other terms ensures that the coefficients of X, Y, and 20 terms are sufficiently small. In this case, (5
)ceremony.
以下余白
の行列式で表わすことができ、この（６）式より補助コ
イル（Ｉｌｌ（１１１体の各補助コイルヘの印加電流を
決定すればよい。It can be expressed by the determinant of the margin below, and the applied current to each of the 111 auxiliary coils can be determined from this equation (6).
（ト）発明の効果
本発明によれば、磁気ヨークによる影響を考慮して決定
した磁場を形成するような電流が印加されている補助コ
イル群を設けたので、一対の永久磁石及び該磁石を磁気
的に結合する磁気ヨークからなる静磁界発生手段によっ
て形成した静磁界の均一度をより高く設定することが可
能である。(G) Effects of the Invention According to the present invention, a group of auxiliary coils to which a current is applied that forms a magnetic field determined by taking into account the influence of the magnetic yoke is provided, so that the pair of permanent magnets and the magnet are It is possible to set higher uniformity of the static magnetic field generated by the static magnetic field generating means consisting of magnetically coupled magnetic yokes.
第１図（＆）及びΦ）は本発明の該磁気共鳴撮像装置に
おける静磁界発生手段を一部破断して示す部分上面図及
び側面図、第２図は補助コイル体を示す上面図、第３図
は一般的な補助コイルの形状を示す模式図である。
（２）・・・永久磁石、（５）・・・磁気ヨーク、 ｔ
ｔｎ・・・補助コイル体。1(&) and Φ) are a partial top view and a side view partially cut away showing the static magnetic field generating means in the magnetic resonance imaging apparatus of the present invention, FIG. 2 is a top view showing the auxiliary coil body, and FIG. FIG. 3 is a schematic diagram showing the shape of a general auxiliary coil. (2)...Permanent magnet, (5)...Magnetic yoke, t
tn...Auxiliary coil body.
Claims (1)
共にほぼ密閉された空間を形成する磁気ヨークからなる
静磁界発生手段により上記空間に一様な静磁界を形成し
、上記磁気ヨークに設けた被測定物挿入用の開口より被
測定物を上記静磁界中に設置することにより、上記被測
定物の原子核分布を画像表示する核磁気共鳴撮像装置で
あつて、上記静磁界発生手段は、上記一対の永久磁石の
夫々に近接する配置で、上記静磁界の一様性を補正する
ための複数の補助コイルを具備し、該補助コイルヘの印
加電流は、上記永久磁石の静磁界分布及び補助コイルが
形成する磁場への上記磁気ヨークの影響を打ち消すよう
に決定されることを特徴とする核磁気共鳴撮像装置。(1) A uniform static magnetic field is formed in the space by a static magnetic field generating means consisting of a pair of permanent magnets and a magnetic yoke that magnetically couples the magnets and forms a nearly sealed space. A nuclear magnetic resonance imaging apparatus that displays an image of the distribution of atomic nuclei in the object to be measured by placing the object in the static magnetic field through a provided opening for inserting the object to be measured, wherein the static magnetic field generating means comprises: , a plurality of auxiliary coils are arranged close to each of the pair of permanent magnets to correct the uniformity of the static magnetic field, and the current applied to the auxiliary coils is adjusted according to the static magnetic field distribution of the permanent magnets and the uniformity of the static magnetic field. A nuclear magnetic resonance imaging apparatus characterized in that the auxiliary coil is configured to cancel the influence of the magnetic yoke on the magnetic field formed by the auxiliary coil.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59137799A JPS6117053A (en) | 1984-07-03 | 1984-07-03 | Nuclear magnetic resonance image sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59137799A JPS6117053A (en) | 1984-07-03 | 1984-07-03 | Nuclear magnetic resonance image sensor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS6117053A true JPS6117053A (en) | 1986-01-25 |
Family
ID=15207117
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59137799A Pending JPS6117053A (en) | 1984-07-03 | 1984-07-03 | Nuclear magnetic resonance image sensor |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6117053A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1808126A1 (en) * | 2004-09-30 | 2007-07-18 | Neomax Co., Ltd. | Magnetic field generator for mri |
-
1984
- 1984-07-03 JP JP59137799A patent/JPS6117053A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1808126A1 (en) * | 2004-09-30 | 2007-07-18 | Neomax Co., Ltd. | Magnetic field generator for mri |
| EP1808126A4 (en) * | 2004-09-30 | 2010-05-05 | Hitachi Metals Ltd | Magnetic field generator for mri |
| US7796002B2 (en) | 2004-09-30 | 2010-09-14 | Hitachi Metals, Ltd. | Magnetic field generator for MRI |
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