JPH0394733A - Magnetic field generator for mri - Google Patents
Magnetic field generator for mriInfo
- Publication number
- JPH0394733A JPH0394733A JP1233129A JP23312989A JPH0394733A JP H0394733 A JPH0394733 A JP H0394733A JP 1233129 A JP1233129 A JP 1233129A JP 23312989 A JP23312989 A JP 23312989A JP H0394733 A JPH0394733 A JP H0394733A
- Authority
- JP
- Japan
- Prior art keywords
- magnetic
- permanent magnet
- magnetic field
- piece
- pole piece
- 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
- 239000000696 magnetic material Substances 0.000 claims description 14
- 229910045601 alloy Inorganic materials 0.000 claims description 5
- 239000000956 alloy Substances 0.000 claims description 5
- 239000003822 epoxy resin Substances 0.000 abstract description 3
- 229920000647 polyepoxide Polymers 0.000 abstract description 3
- 229910001004 magnetic alloy Inorganic materials 0.000 abstract 3
- 239000002994 raw material Substances 0.000 abstract 1
- 239000000463 material Substances 0.000 description 6
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 5
- 239000002648 laminated material Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 229910000976 Electrical steel Inorganic materials 0.000 description 2
- 238000005481 NMR spectroscopy Methods 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 2
- 238000004026 adhesive bonding Methods 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000003384 imaging method Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 238000003325 tomography Methods 0.000 description 2
- 229910052779 Neodymium Inorganic materials 0.000 description 1
- 229910052777 Praseodymium Inorganic materials 0.000 description 1
- 229910000828 alnico Inorganic materials 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000013590 bulk material Substances 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000003745 diagnosis Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Landscapes
- Magnetic Resonance Imaging Apparatus (AREA)
Abstract
Description
【発明の詳細な説明】
利用産業分野
この発明は、医療用核磁気共鳴断層撮影装置等に用いら
れる永久磁石を使用した磁界発生装置の改良に係り、永
久磁石構成体とその上に着設する磁極片とが、永久磁石
構或体の各永久磁石単位に柱状ブロックに細分化され、
相互に絶縁して接着一体化して所要形状に組み立て、空
隙内の静磁界強度の均一性を向上させ、かつ傾斜磁界コ
イルによる渦電流の低減を図ったＭＲＩ用磁界発生装置
に関する。[Detailed Description of the Invention] Field of Application This invention relates to an improvement of a magnetic field generating device using a permanent magnet used in a medical nuclear magnetic resonance tomography device, etc. The magnetic pole piece is subdivided into columnar blocks for each permanent magnet unit of the permanent magnet structure,
The present invention relates to a magnetic field generating device for MRI which is mutually insulated and bonded together and assembled into a desired shape to improve the uniformity of the static magnetic field strength within the air gap and to reduce eddy currents caused by gradient magnetic field coils.
背景技術
医療用核磁気共鳴断層撮影装置（以下ＭＲＩという）は
、強力な磁界を形戒する磁界発生装置の空隙内に、被検
者の一部または全部を挿入して、対象物の断層イメージ
を得てその組織の性質まで描き出すことができる装置で
ある。BACKGROUND TECHNOLOGY A medical nuclear magnetic resonance tomography apparatus (hereinafter referred to as MRI) generates a tomographic image of an object by inserting part or all of the subject into the gap of a magnetic field generator that generates a strong magnetic field. This is a device that can be used to draw out the characteristics of the tissue.
上記ＭＲＩ用の磁界発生装置において、空隙は被検者の
一部または全部が挿入できるだけの広さが必要であり、
かつ鮮明な断層イメージを得るために、通常、空隙内の
撮像視野内には、０．０５〜２。ＯＴでかつ１ｘｌＯ’
以下の精度を有する安定した強力な均一磁界を形戒する
ことが要求される。In the above magnetic field generation device for MRI, the gap must be wide enough to allow part or all of the subject to be inserted;
In order to obtain a clear tomographic image, the imaging field of view within the gap is usually 0.05 to 2. OT and 1xlO'
It is required to form a stable, strong, uniform magnetic field with the following accuracy:
ＭＲＩに用いる磁界発生装置として、第３図に示す如く
、Ｆｅ−Ｂ−Ｒ系磁石を用いた一対の永久磁石構或体（
ＩＸＩ）の各々の一方端に磁極片（２Ｘ２）を固着して
対向させ、他方端を継鉄（３１＋３２）にて連結し、磁
極片（２Ｘ２）間の空隙（４）内に、静磁界を発生させ
る構成が知られている。As shown in Fig. 3, the magnetic field generator used in MRI consists of a pair of permanent magnet structures (
A magnetic pole piece (2X2) is fixed to one end of each of the magnetic pole pieces (2X2) to face each other, and the other end is connected with a yoke (31+32), and a static magnetic field is applied in the gap (4) between the magnetic pole pieces (2X2). A configuration for generating this is known.
磁極片（２Ｘ２）には、空隙（４）内における磁界分布
の均一度を向上させるために、周辺部に環状突起（５）
を設けてあり、通常、電磁軟鉄、純鉄等の磁性材料を削
り出した板状のバルク（一体物）から構或される（特開
昭６０−８８４０７号公報）。The magnetic pole piece (2X2) has an annular protrusion (5) on the periphery in order to improve the uniformity of the magnetic field distribution within the air gap (4).
It is usually constructed from a plate-shaped bulk (integral object) cut out of a magnetic material such as electromagnetic soft iron or pure iron (Japanese Patent Application Laid-open No. 88407/1983).
被検体が入る空隙（４）の高さを高く確保するため、各
磁極片（２Ｘ２）の近傍に配置される傾斜磁界コイル（
６）は、空隙（４）内の位置情報を得るために、通常ｘ
， ｙ， ｚの３方向に対応する３組のコイル群からな
るが、図示（第３図）においては簡略して記載している
。In order to ensure a high height of the air gap (4) in which the subject enters, a gradient magnetic field coil (
6) is usually x in order to obtain position information within the gap (4)
It consists of three sets of coil groups corresponding to the three directions of , y, and z, but they are shown in a simplified manner in the illustration (Fig. 3).
この傾斜磁界コイル（６）に、パルス電流を印加するこ
とによって短時間で所望方向に傾斜した磁界を発生する
ことができる。By applying a pulse current to this gradient magnetic field coil (6), a magnetic field tilted in a desired direction can be generated in a short time.
従来技術の問題点
傾斜磁界コイル（６）にパルス電流を流すと、磁極片（
２）は前述した如く板状のバルクから構成されるため、
その電流の立上り、立下がり時に発生するパルス状の磁
界により、磁極片（２Ｘ２）に渦電流が発生する。Problems with the conventional technology When a pulse current is passed through the gradient magnetic field coil (6), the magnetic pole piece (
2) is composed of a plate-shaped bulk as mentioned above, so
An eddy current is generated in the magnetic pole piece (2×2) due to the pulsed magnetic field generated when the current rises and falls.
この渦電流は、傾斜磁界コイル（６）にて形成される磁
界と反対方向の磁界を形成するため、傾斜磁界が所定の
強度に達するのに多くの時間を要することになり、必然
的に高速スキャン等の新イメージングテクニックが使用
できず診断時間が長くなる。また、通常においても直像
のぼけの原因になり、診断を妨げる。This eddy current forms a magnetic field in the opposite direction to the magnetic field formed by the gradient magnetic field coil (6), so it takes a long time for the gradient magnetic field to reach a predetermined strength, which inevitably results in a high speed. New imaging techniques such as scans cannot be used, increasing diagnostic time. Further, even in normal conditions, it causes blurring of the direct image, which hinders diagnosis.
かかる時間を短縮するために、容量の大きな電源を用い
る手段もあるが効率が悪く、装置全体のコストを高騰さ
せる要因ともなっていた。In order to shorten this time, there is a method of using a power source with a large capacity, but this is inefficient and causes a rise in the cost of the entire device.
上述の問題を解決する手段として、磁極片として軟質磁
性薄板を一方向に積層してなる平板状の積層体を、その
積層方向が互いに略９０度異なるよう二層に配置一体化
した構成のものを用いた磁界発生装置が提案（特開昭６
１−２０３６０５号）されている。As a means to solve the above-mentioned problem, a flat laminate made of soft magnetic thin plates laminated in one direction as a magnetic pole piece is arranged and integrated into two layers so that the lamination directions differ by approximately 90 degrees from each other. A magnetic field generator using
1-203605).
しかし、渦電流の発生を防ぐためには、積層体を構戒す
る軟質磁性薄板を十分に薄くする必要があり、さらに、
実用化するためには２０００〜３０００枚の軟質磁性薄
板を積層する必要があり、空隙内の磁界均一度が低下す
る。However, in order to prevent the generation of eddy currents, it is necessary to make the soft magnetic thin plates that form the laminated body sufficiently thin.
In order to put it into practical use, it is necessary to laminate 2,000 to 3,000 soft magnetic thin plates, which reduces the uniformity of the magnetic field within the gap.
発明の目的
この発明は、上記現状に鑑み提案するもので、加工、製
造が容易で、かつ空隙内の磁界均一度を低下させること
なく、渦電流の発生を防ぐことができる磁極片を配置し
た磁界発生装置の提供を目的とするものである。Purpose of the Invention The present invention is proposed in view of the above-mentioned current situation, and has magnetic pole pieces arranged that are easy to process and manufacture and can prevent the generation of eddy currents without reducing the uniformity of the magnetic field within the air gap. The purpose is to provide a magnetic field generator.
発明の概要
この発明は、磁界発生装置において、永久磁石構成体と
その上に着設する磁極片とを、永久磁石構成体の各永久
磁石単位に柱状ブロックに相互に絶縁して細分化したこ
とにより、空隙内の磁界均一度を低下させることなく、
渦電流防止を可能にし、また、製造が容易なることを知
見し、この発明を完威したものである。Summary of the Invention The present invention provides a magnetic field generating device in which a permanent magnet structure and a magnetic pole piece attached thereon are subdivided into columnar blocks for each permanent magnet of the permanent magnet structure and insulated from each other. without reducing the magnetic field uniformity within the air gap.
It was discovered that this invention made it possible to prevent eddy currents and was easy to manufacture.
すなわち、この発明は、
空隙を形成して対向する一対の永久磁石構成体を継鉄で
磁気的結合し、各永久磁石構成体の空隙対向面に、周辺
部に環状突起を有する磁極片を固着し、該空隙に磁界を
発生させるＭＲＩ用磁界発生装置において、
磁石合金小片に磁性材小片を固着載置した後に着磁した
永久磁石を、相互に絶縁した状態で接着して継鉄に配列
し組み立てた永久磁石構或体を特徴とするＭＲＩ用磁界
発生装置である。That is, the present invention magnetically couples a pair of permanent magnet structures facing each other with an air gap formed therein using a yoke, and fixes a magnetic pole piece having an annular protrusion on the periphery to the surface of each permanent magnet structure that faces the air gap. In a magnetic field generator for MRI that generates a magnetic field in the air gap, a small piece of magnetic material is firmly placed on a small piece of magnet alloy, and then the magnetized permanent magnets are bonded and arranged in a yoke in a mutually insulated state. This is a magnetic field generating device for MRI characterized by an assembled permanent magnet structure.
換言すれば、
永久磁石構成体の各永久磁石上に磁極片を構或する磁性
材小片が固着載置されて隣接する永久磁石同志、磁性材
小片同志が相互に接着剤で絶縁した状態で一体化された
ことを特徴とするＭＲＪ用磁界発生装置であり，
発明の構或
この発明において、磁気回路は、空隙を形成して対向す
る一対の永久磁石構或体を継鉄で磁気的結合し、各永久
磁石構成体の空隙対向面に磁極片を固着した構或であれ
ば、いかなる構或であってもよく、永久磁石の磁気特性
、形状寸法、継鉄の形状寸法及び所要空隙の大きさ等に
応じて、例えば、磁極片の構造等を適宜選定することが
望ましい。In other words, the magnetic material pieces constituting the magnetic pole pieces are fixedly placed on each permanent magnet of the permanent magnet structure, and the adjacent permanent magnets and magnetic material pieces are insulated from each other with adhesive and integrated. In this invention, the magnetic circuit magnetically couples a pair of permanent magnet structures facing each other with a gap formed therebetween by means of a yoke. Any structure may be used as long as a magnetic pole piece is fixed to the surface facing the air gap of each permanent magnet structure, and the magnetic properties and dimensions of the permanent magnet, the shape and dimensions of the yoke, and the size of the required air gap may be used. For example, it is desirable to appropriately select the structure of the magnetic pole piece, etc., depending on the magnetic field.
かかる磁気回路に用いる磁石構或体の永久磁石は、フエ
ライト磁石、アルニコ系磁石、希土類コバルト系磁石が
使用できるが、特に、ＲとしてＮｄやＰｒを中心とする
資源的に豊富な軽希土類を用い、Ｂ， Ｆｅを主威分と
して３０ＭＧＯｅ以上の極めて高いエネルギー積を示す
、Ｆｅ−Ｂ−Ｒ系永久磁石を使用することにより、著し
く小型化することができる。As the permanent magnet of the magnetic structure used in such a magnetic circuit, ferrite magnets, alnico magnets, and rare earth cobalt magnets can be used, but in particular, resource-rich light rare earths such as Nd and Pr can be used as R. , B, By using a Fe-B-R permanent magnet that exhibits an extremely high energy product of 30 MGOe or more with Fe as the main component, it is possible to significantly reduce the size.
この発明は、永久磁石構成体とその上に着設する磁極片
とを、永久磁石構成体の各永久磁石単位に柱状ブロック
に、相互に絶縁して細分化したことを特徴としており、
磁極片が電気的に絶縁されて細分化されたことにより渦
電流の発生を防止したもので、細分化された各小片面積
は
１０ｃｍｘｌＯｃｍ以下が好ましい。The present invention is characterized in that the permanent magnet structure and the magnetic pole pieces attached thereon are subdivided into columnar blocks for each permanent magnet of the permanent magnet structure and are insulated from each other.
The magnetic pole pieces are electrically insulated and segmented to prevent the generation of eddy currents, and the area of each segmented segment is preferably 10 cm x lOcm or less.
゛また、永久磁石構成体の各永久磁石単位が、さらに小
永久磁石の集合体である場合があり、特に、環状突起部
側は最外周であるため、各永久磁石単位を円弧状に形戒
することから小永久磁石の集合体となる場合があり、永
久磁石の上に磁極片が乗らない部分も生じる。゛In addition, each permanent magnet unit of the permanent magnet structure may be an aggregate of smaller permanent magnets, and in particular, since the annular protrusion side is the outermost periphery, each permanent magnet unit is shaped like an arc. As a result, it may become an aggregate of small permanent magnets, and there may be parts where the magnetic pole piece does not sit on the permanent magnet.
この発明において、磁極片の空隙側周辺部に環状突起を
設けた構戒とすることにより、磁束を所要空隙に集中さ
せかつ均一度を向上させることができ、設定した磁極片
形状、寸法並びに分割位置などに応じて、予め磁性材小
片を所要の寸法形状に加工しておくことにより、磁極片
組み立て後の磁極片の切削あるいは研摩加工を省略でき
る。In this invention, by providing an annular protrusion on the periphery of the magnetic pole piece on the air gap side, magnetic flux can be concentrated in the required air gap and uniformity can be improved. By processing the small pieces of magnetic material in advance into a required size and shape depending on the position, etc., cutting or polishing of the magnetic pole piece after assembly of the magnetic pole piece can be omitted.
この発明において、磁極片の材質は、種々の磁性材のバ
ルクからなるもの、ラミネートしたもの、ケイ素鋼板の
積層材、異材質等を複合したもの等軟質磁性材料を適宜
選定でき、さらに、磁界の均一度向上を目的に、中央部
に円形凸状部や断面台形状の突起部を設けたり、磁極片
の所要位置に、磁界の均一度調整を目的に、磁性材また
は磁石からなる磁界調整片を着設しても良い。In this invention, the material of the magnetic pole piece can be appropriately selected from soft magnetic materials such as bulk materials of various magnetic materials, laminated materials, laminated materials of silicon steel plates, composite materials of different materials, etc. For the purpose of improving uniformity, a circular convex part or a protrusion with a trapezoidal cross section is provided at the center, and magnetic field adjustment pieces made of magnetic material or magnets are installed at desired positions of the magnetic pole pieces for the purpose of adjusting the uniformity of the magnetic field. may be installed.
さらに、磁界の均一度向上を目的に、予め行った空隙内
の磁界分布解析などに基づいて、調整を要する箇所に配
置する磁性材小片高さを予め所要高さに調整しておくこ
とにより、量産時、組み立て後の磁界調整片の着設等を
省略することができる。Furthermore, in order to improve the uniformity of the magnetic field, the height of the small pieces of magnetic material placed in the areas that require adjustment can be adjusted to the required height based on the magnetic field distribution analysis in the air gap that has been conducted in advance. During mass production, installation of magnetic field adjustment pieces after assembly can be omitted.
図面に基づく発明の開示
第１図と第２図はこの発明による永久磁石構成体と磁極
片の一実施例を示す上面図と横断面図である。DISCLOSURE OF THE INVENTION BASED ON THE DRAWINGS FIGS. 1 and 2 are a top view and a cross-sectional view showing one embodiment of a permanent magnet structure and a magnetic pole piece according to the present invention.
第１図に示す磁界発生装置の永久磁石構成体（１）とそ
の上に着設する磁極片（２）は、円盤状で磁極片の空隙
側周辺部に環状突起（５）を設けた構成からなり、永久
磁石構成体（１）と磁極片（２）は、永久磁石構成体（
１）の各永久磁石（１ａ）単位に柱状ブロックに分割さ
れ、永久磁石（１ａ）に磁性材小片（２ａＸ２ｂＸ２ｃ
）が固着載置されて、隣接磁性材小片（２ａＸ２ｂＸ２
ｃ）同志がエボキシ樹脂等で相互に絶縁した状態で接着
してある。The permanent magnet structure (1) of the magnetic field generating device shown in Fig. 1 and the magnetic pole piece (2) attached thereon are disc-shaped and have an annular protrusion (5) on the periphery of the magnetic pole piece on the air gap side. The permanent magnet structure (1) and the magnetic pole piece (2) are composed of the permanent magnet structure (
Each permanent magnet (1a) of 1) is divided into columnar blocks, and a small piece of magnetic material (2aX2bX2c) is attached to the permanent magnet (1a).
) is firmly placed, and the adjacent magnetic material pieces (2aX2bX2
c) The members are bonded together with epoxy resin or the like while insulating them from each other.
組み立て方法を説明すると、まず、永久磁石（１ａ）素
材である磁石合金小片に、設定した磁極片（２）形状、
寸法並びに分割位置などに応じて、予め所要の寸法形状
に加工した磁性材小片（２ａＸ２ｂＸ２ｃ）を載置し接
着した後、各磁石合金小片を着磁して永久磁石（１ａ）
となし、これを継鉄（３１）上で、順次エポキシ樹脂等
で接着して配列し、所要形状の磁極片（２）に組み立て
るもので、磁極片（２）を構戒する多数の磁性材小片（
２ａＸ２ｂＸ２ｃ）が相互に絶縁された状態で接着され
ている。To explain the assembly method, first, attach the set magnetic pole piece (2) shape to a small piece of magnet alloy that is the permanent magnet (1a) material,
After placing and gluing small pieces of magnetic material (2aX2bX2c) that have been pre-processed into the required size and shape according to the dimensions and division positions, each small piece of magnet alloy is magnetized to form a permanent magnet (1a).
These are then arranged on a yoke (31) by gluing them with epoxy resin, etc., and assembled into a magnetic pole piece (2) of the desired shape. Small pieces (
2aX2bX2c) are bonded together in a mutually insulated state.
ここでは、磁極片（２）が碁盤の目の如く分割してあり
、細分化は要求される磁界の均一度、渦電流の低減量に
応じて、任意のパターンを取ることができる。Here, the magnetic pole piece (2) is divided like a checkerboard, and the subdivision can take any pattern depending on the required uniformity of the magnetic field and the amount of reduction of eddy current.
第２図に示す磁界発生装置の永久磁石構成体（１）と磁
極片（２）は、第１図の構戒と同等であるが、第１図に
示す磁極片（２）材料が軟質磁性のバルク材からなるの
に対し、第２図の磁極片（２）はケイ素鋼板の積層材か
らなる。The permanent magnet structure (1) and the magnetic pole piece (2) of the magnetic field generator shown in Fig. 2 are the same as those shown in Fig. 1, but the material of the magnetic pole piece (2) shown in Fig. 1 is soft magnetic. In contrast, the pole piece (2) in FIG. 2 is made of a laminated material of silicon steel plates.
発明の効果
従来のバルク材で構戒した磁極片は、高周波（ラジオ周
波数の１００〜数ＫＨｚ ）を受けても、渦電流が発生
するが、この発明よる磁極片は、全バルクの磁極に比べ
渦電流を低減できるため、ＭＲＩ用に使用される場合、
その傾斜磁場コイルのパルスを高速にすることができる
。また、得られるＭＨＩ画像にも歪が無くなり、ＭＨＩ
としての性能が大幅に向上する。Effects of the Invention Although conventional magnetic pole pieces made of bulk materials generate eddy currents even when subjected to high frequencies (100 to several KHz of radio frequency), the magnetic pole pieces according to the present invention generate eddy currents compared to magnetic poles made of all bulk material. When used for MRI because it can reduce eddy currents,
The pulse of the gradient magnetic field coil can be made high speed. In addition, there is no distortion in the MHI image obtained, and the MHI
performance will be significantly improved.
また、所要形状に加工した磁性材小片を磁石合金小片に
載置してからこれを着磁し、継鉄上で接着組立てするこ
とができるため、磁気回路組立て後の磁極片の整形加工
が不要になる。In addition, a small piece of magnetic material processed into the desired shape can be placed on a small piece of magnet alloy, magnetized, and assembled by adhesive on a yoke, so there is no need to shape the magnetic pole pieces after assembling the magnetic circuit. become.
第１図と第２図はこの発明による永久磁石構成体と磁極
片の一実施例を示す上面図と横断面図である。
第３図は従来の磁界発生装置の縦断説明図である。
１・・・永久磁石構或体、２・・・磁極片、３１，３２
・・・継鉄、４・・・空隙、５・・・環状突起、６・・
・傾斜磁界コイル。1 and 2 are a top view and a cross-sectional view showing one embodiment of a permanent magnet structure and a magnetic pole piece according to the present invention. FIG. 3 is a longitudinal cross-sectional view of a conventional magnetic field generator. 1... Permanent magnet structure, 2... Magnetic pole piece, 31, 32
...Yoke, 4...Gap, 5...Annular protrusion, 6...
・Gradient magnetic field coil.
Claims (1)
磁気的結合し、各永久磁石構成体の空隙対向面に、周辺
部に環状突起を有する磁極片を固着し、該空隙に磁界を
発生させるＭＲＩ用磁界発生装置において、 磁石合金小片に磁性材小片を固着載置した後に着磁した
永久磁石を、相互に絶縁した状態で接着して継鉄に配列
し組み立てた永久磁石構成体を特徴とするＭＲＩ用磁界
発生装置。[Claims] 1. A pair of permanent magnet structures facing each other with a gap formed therebetween are magnetically coupled by a yoke, and a magnetic pole piece having an annular protrusion at the periphery is provided on the surface of each permanent magnet structure facing the gap. In an MRI magnetic field generation device that generates a magnetic field in the air gap, a small piece of magnetic material is fixedly placed on a small piece of magnet alloy, and then the magnetized permanent magnets are adhered and arranged in a yoke in a mutually insulated state. A magnetic field generator for MRI characterized by a permanent magnet structure assembled with
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1233129A JPH0394733A (en) | 1989-09-08 | 1989-09-08 | Magnetic field generator for mri |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1233129A JPH0394733A (en) | 1989-09-08 | 1989-09-08 | Magnetic field generator for mri |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0394733A true JPH0394733A (en) | 1991-04-19 |
Family
ID=16950200
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1233129A Pending JPH0394733A (en) | 1989-09-08 | 1989-09-08 | Magnetic field generator for mri |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0394733A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0978727A2 (en) * | 1998-08-06 | 2000-02-09 | Sumitomo Special Metals Company Limited | Magnetic field generator for MRI, method for assembling the same and method for assembling a magnet unit for the same |
| EP1058933A1 (en) * | 1998-02-09 | 2000-12-13 | Odin Medical Technologies Ltd. | A method for designing open magnets and open magnetic apparatus for use in mri/mrt probes |
| US6828891B2 (en) * | 2002-07-25 | 2004-12-07 | Ge Medical Systems Global Technology Company, Llc | Method for assembling magnetic members for magnetic resonance imaging magnetic field generator |
| JP2007503959A (en) * | 2003-05-23 | 2007-03-01 | シーメンス アクチエンゲゼルシヤフト | Magnet apparatus for magnetic resonance imaging having an axially adjustable rose shim ring |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63105745A (en) * | 1986-10-22 | 1988-05-11 | 株式会社東芝 | Magnetic resonance imaging apparatus |
| JPH01104252A (en) * | 1987-10-16 | 1989-04-21 | Sanyo Electric Co Ltd | Magnetic resonance imaging apparatus |
-
1989
- 1989-09-08 JP JP1233129A patent/JPH0394733A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63105745A (en) * | 1986-10-22 | 1988-05-11 | 株式会社東芝 | Magnetic resonance imaging apparatus |
| JPH01104252A (en) * | 1987-10-16 | 1989-04-21 | Sanyo Electric Co Ltd | Magnetic resonance imaging apparatus |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1058933A1 (en) * | 1998-02-09 | 2000-12-13 | Odin Medical Technologies Ltd. | A method for designing open magnets and open magnetic apparatus for use in mri/mrt probes |
| EP1058933A4 (en) * | 1998-02-09 | 2006-03-01 | Odin Medical Technologies Ltd | A method for designing open magnets and open magnetic apparatus for use in mri/mrt probes |
| EP0978727A2 (en) * | 1998-08-06 | 2000-02-09 | Sumitomo Special Metals Company Limited | Magnetic field generator for MRI, method for assembling the same and method for assembling a magnet unit for the same |
| EP0978727A3 (en) * | 1998-08-06 | 2001-05-02 | Sumitomo Special Metals Company Limited | Magnetic field generator for MRI, method for assembling the same and method for assembling a magnet unit for the same |
| US6336989B1 (en) | 1998-08-06 | 2002-01-08 | Sumitomo Special Metals Co., Ltd. | Magnetic field generator for MRI, method for assembling the same, and method for assembling a magnet unit for the same |
| US6650214B2 (en) | 1998-08-06 | 2003-11-18 | Sumitomo Special Metals Co., Ltd. | Magnetic field generator for MRI, method for assembling the same, and method for assembling a magnet unit for the same |
| US7065860B2 (en) | 1998-08-06 | 2006-06-27 | Neomax Co., Ltd. | Method for assembling a magnetic field generator for MRI |
| US6828891B2 (en) * | 2002-07-25 | 2004-12-07 | Ge Medical Systems Global Technology Company, Llc | Method for assembling magnetic members for magnetic resonance imaging magnetic field generator |
| JP2007503959A (en) * | 2003-05-23 | 2007-03-01 | シーメンス アクチエンゲゼルシヤフト | Magnet apparatus for magnetic resonance imaging having an axially adjustable rose shim ring |
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