JPH05132A - Magnetic resonance imaging equipment - Google Patents
Magnetic resonance imaging equipmentInfo
- Publication number
- JPH05132A JPH05132A JP3151772A JP15177291A JPH05132A JP H05132 A JPH05132 A JP H05132A JP 3151772 A JP3151772 A JP 3151772A JP 15177291 A JP15177291 A JP 15177291A JP H05132 A JPH05132 A JP H05132A
- Authority
- JP
- Japan
- Prior art keywords
- magnetic field
- generating means
- field generating
- gradient magnetic
- resonance imaging
- 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.)
- Granted
Links
Landscapes
- Magnetic Resonance Imaging Apparatus (AREA)
Abstract
(57)【要約】
【構成】 ボビン１０の外側には複数の分割部材８が配
置されている。この分割部材８はボビン１０よりも一ま
わり大きな円筒をその軸方向に分割したものであり、ボ
ビン１０に密着するようになっている。分割部材８はバ
ンド１３によってボビン１０に強固に固定される。
【効果】 分割部材８はボビン１０の振動を抑制しよう
とする役目をはたす。そのためボビン１０の低振動化が
図れ、磁気共鳴イメージング装置が低騒音化できる。
(57) [Summary] [Structure] A plurality of dividing members 8 are arranged outside the bobbin 10. The dividing member 8 is a cylinder that is one size larger than the bobbin 10 and is divided in the axial direction, and is in close contact with the bobbin 10. The split member 8 is firmly fixed to the bobbin 10 by the band 13. [Effect] The dividing member 8 serves to suppress the vibration of the bobbin 10. Therefore, the bobbin 10 can be reduced in vibration, and the magnetic resonance imaging apparatus can be reduced in noise.
Description
【０００１】[0001]
【産業上の利用分野】本発明は、磁気共鳴イメージング
装置におけるコイル支持体の振動防止構造に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for preventing vibration of a coil support in a magnetic resonance imaging apparatus.
【０００２】[0002]
【従来の技術】従来の医療用磁気共鳴イメージング装置
では、特開昭６２−２６１１０５号公報や特開昭６２−
２６９９０６号公報に記載されているように、鞍形状の
一対の傾斜磁場コイルが、弾性率の非常に大きなエポキ
シ樹脂等の材料で製作した円筒状の支持体であるボビン
上に直接固定されていた。この傾斜磁場コイルを、空洞
状をしたボア内の均一静磁場内に配置し、ボア内の被検
査者の２次元断面画像処理を行うために傾斜磁場コイル
に周期的なパルス電流を流し、静磁場中に周期的な傾斜
磁場分布を与えるようにしていた。従って、パルス電流
を流す時には、静磁場によって傾斜磁場コイルが円周部
に半径方向の電磁力が生じる。この電磁力がボビンを加
振する力となり、ボビンが振動して騒音を発生してい
た。2. Description of the Related Art A conventional magnetic resonance imaging apparatus for medical use is disclosed in JP-A-62-261105 and JP-A-62-261105.
As described in Japanese Patent No. 269906, a pair of saddle-shaped gradient magnetic field coils are directly fixed on a bobbin which is a cylindrical support body made of a material such as epoxy resin having a very large elastic modulus. . This gradient magnetic field coil is placed in a uniform static magnetic field in a hollow bore, and a periodic pulse current is applied to the gradient magnetic field coil to perform 2D cross-sectional image processing of the subject in the bore. A periodic gradient magnetic field distribution was given in the magnetic field. Therefore, when a pulse current is passed, the static magnetic field causes a radial electromagnetic force in the circumferential portion of the gradient magnetic field coil. This electromagnetic force acts as a force to excite the bobbin, causing the bobbin to vibrate and generate noise.
【０００３】一方、従来の医療用磁気共鳴イメージング
装置では、特開昭６１−２７９２３８号公報に記載され
ているように、クライオスタット内側に形成されたボア
内の静磁場を直角に切る断面のＸＹ方向に、互いに対向
するように配置された対の鞍形状の傾斜磁場コイルを、
弾性率の非常に大きなエポキシ樹脂等で製作した円筒状
の支持体であるボビン上に防振ゴムを介して固定してい
た。この傾斜磁場コイルに周期的な傾斜磁場を発生させ
て、被検査者の３次元断面画像信号を得ていた。このパ
ルス電流を流す時、ボア内の静磁場を横切る方向に電流
が流れるコイルに、フレミングの左手の法則に従った電
磁力が働き、このためにボビンにパルス的な荷重がかか
っていた。この荷重によりボビンが振動して騒音を発生
していた。しかし、この公知例においてはコイルとボビ
ンとの間に防振ゴムを介しているためコイルからボビン
に伝達される力が減少する。そのため、特開昭６２−２
６１１０５号公報や特開昭６２−２２９９０６号公報よ
りもこの公知例の方が騒音面では有利となる。この他傾
斜磁場コイルの支持の工夫として特開昭６３−１５８０
４７号公報、同６２−２３９５０３号公報記載の技術が
ある。On the other hand, in the conventional magnetic resonance imaging apparatus for medical use, as described in Japanese Patent Laid-Open No. 61-279238, the cross section of the static magnetic field in the bore formed inside the cryostat at right angles to the XY direction. , A pair of saddle-shaped gradient magnetic field coils arranged to face each other,
It was fixed via a vibration-proof rubber on a bobbin, which is a cylindrical support made of epoxy resin having a very high elastic modulus. A periodic gradient magnetic field is generated in this gradient magnetic field coil to obtain a three-dimensional sectional image signal of the subject. When this pulsed current was passed, an electromagnetic force according to Fleming's left-hand rule acted on the coil in which a current flowed across the static magnetic field in the bore, and a pulsed load was applied to the bobbin for this reason. This load vibrated the bobbin and generated noise. However, in this known example, since the vibration-proof rubber is interposed between the coil and the bobbin, the force transmitted from the coil to the bobbin is reduced. Therefore, JP-A-62-2
This known example is more advantageous in terms of noise than JP-A-61105 and JP-A-62-229906. In addition, as a device for supporting the gradient magnetic field coil, JP-A-63-1580
47 and 62-239503.
【０００４】[0004]
【発明が解決しようとする課題】以上のような磁気共鳴
イメージング装置では傾斜磁場コイルがボビン上に直接
固定されていたため、パルス電流を流すと、電磁力によ
るパルス的な荷重によってボビンが振動してボビン全体
から大きな音が発生し、被検査者に不快感を与えてしま
う問題があった。この場合に発生する音の周波数域は、
２５０Ｈｚ〜８ＫＨｚの低周波数から高周波数域までの
全般にわたっていた。また、ボビンと傾斜磁場コイルの
間に防振ゴムを挾むと騒音は緩和されるが、傾斜磁場コ
イルをテープ状の固着体で固定しているため、引張り方
向以外の剛性が不足し、傾斜磁場コイル自身が振動し、
ボア内の磁場分布に変化が生じ、実際と異なる、像の歪
が画像に生じてしまうという問題があった。In the above magnetic resonance imaging apparatus, since the gradient magnetic field coil is directly fixed on the bobbin, when a pulse current is applied, the bobbin vibrates due to a pulsed load due to electromagnetic force. There is a problem that a loud sound is generated from the entire bobbin, which gives the examinee an unpleasant feeling. The frequency range of the sound generated in this case is
It was wide ranging from a low frequency of 250 Hz to 8 KHz to a high frequency range. Also, sandwiching a vibration-proof rubber between the bobbin and the gradient magnetic field coil reduces noise, but since the gradient magnetic field coil is fixed with a tape-shaped fixed body, the rigidity other than in the pulling direction is insufficient, and the gradient magnetic field is reduced. The coil itself vibrates,
There is a problem in that the magnetic field distribution in the bore changes, causing image distortion that is different from the actual one.
【０００５】本発明の目的は傾斜磁場の電磁力によって
生じる騒音を低減でき、かつ、高画質の画像を形成でき
る磁気共鳴イメージング装置を提供することにある。An object of the present invention is to provide a magnetic resonance imaging apparatus capable of reducing noise generated by the electromagnetic force of a gradient magnetic field and forming a high quality image.
【０００６】[0006]
【課題を解決するための手段】上記目的を達成するため
に、ボビン軸方向に少くとも２分割以上分割した部材
（以下分割部材とよぶ）を基本となる円筒上のボビン
（以下単にボビンとよぶ）に積層し、該分割部材をバン
ド状の固定部材によってボビンに固定する。In order to achieve the above object, a cylindrical bobbin (hereinafter simply referred to as bobbin) which is basically a member divided into at least two or more parts in the axial direction of the bobbin (hereinafter referred to as a divided member). ), And the divided member is fixed to the bobbin by a band-shaped fixing member.
【０００７】すなわち本発明は、円筒空間に均一な高磁
場を供給する強磁場発生手段と、該円筒空間内の半径方
向に傾斜磁場分布を供給する傾斜磁場発生手段と、該傾
斜磁場発生手段を前記円筒空間内の所定の位置に固定す
る支持体とを備えた磁気共鳴イメージング装置におい
て、前記傾斜磁場発生手段と前記支持体との間に該支持
体の剛性と同等の分割部材を設けたことを特徴とするも
のである。That is, the present invention comprises a strong magnetic field generating means for supplying a uniform high magnetic field to a cylindrical space, a gradient magnetic field generating means for supplying a gradient magnetic field distribution in the radial direction in the cylindrical space, and the gradient magnetic field generating means. In a magnetic resonance imaging apparatus including a support body fixed at a predetermined position in the cylindrical space, a dividing member having rigidity equal to that of the support body is provided between the gradient magnetic field generating means and the support body. It is characterized by.
【０００８】また、本発明は、円筒空間に均一な高磁場
を供給する強磁場発生手段と、該円筒空間内の半径方向
に傾斜磁場分布を供給する傾斜磁場発生手段と、該傾斜
磁場発生手段を前記円筒空間内の所定の位置に固定する
支持体とを備えた磁気共鳴イメージング装置において、
前記傾斜磁場発生手段と前記支持体との間に支持体より
も剛性の小さな弾性体と該支持体の剛性と同等の分割部
材とを設けたことを特徴とするものである。Further, according to the present invention, a strong magnetic field generating means for supplying a uniform high magnetic field to the cylindrical space, a gradient magnetic field generating means for supplying a gradient magnetic field distribution in the radial direction in the cylindrical space, and the gradient magnetic field generating means. In a magnetic resonance imaging apparatus comprising a support for fixing at a predetermined position in the cylindrical space,
An elastic body having a rigidity smaller than that of the support and a dividing member having a rigidity equal to that of the support are provided between the gradient magnetic field generating means and the support.
【０００９】また本発明は、円筒空間に均一な高磁場を
供給する強磁場発生手段と、該円筒空間内の半径方向に
傾斜磁場分布を供給する傾斜磁場発生手段と、該傾斜磁
場発生手段を前記円筒空間内の所定の位置に固定する支
持体とを備えた磁気共鳴イメージング装置において、前
記傾斜磁場発生手段と前記支持体との間に該支持体より
も剛性の小さな弾性体を設け、該支持体の内壁に該支持
体の剛性と同等の分割部材を設けたことを特徴とするも
のである。The present invention further comprises a strong magnetic field generating means for supplying a uniform high magnetic field to the cylindrical space, a gradient magnetic field generating means for supplying a gradient magnetic field distribution in the radial direction within the cylindrical space, and the gradient magnetic field generating means. In a magnetic resonance imaging apparatus including a support body fixed at a predetermined position in the cylindrical space, an elastic body having a rigidity smaller than that of the support body is provided between the gradient magnetic field generating means and the support body, It is characterized in that a dividing member having the same rigidity as the support is provided on the inner wall of the support.
【００１０】また本発明は、円筒空間に均一な高磁場を
供給する強磁場発生手段と、該円筒空間内の半径方向に
傾斜磁場分布を供給する傾斜磁場発生手段と、該傾斜磁
場発生手段を前記円筒空間内の所定の位置に固定する支
持体とを備えた磁気共鳴イメージング装置において、該
支持体が円筒を分割した複数の分割部材と該分割部材を
連結する減衰材とより成ることを特徴とするものであ
る。The present invention further comprises a strong magnetic field generating means for supplying a uniform high magnetic field to the cylindrical space, a gradient magnetic field generating means for supplying a gradient magnetic field distribution in the radial direction within the cylindrical space, and the gradient magnetic field generating means. In a magnetic resonance imaging apparatus including a support body fixed at a predetermined position in the cylindrical space, the support body is composed of a plurality of division members that divide the cylinder and an attenuating member that connects the division members. It is what
【００１１】また本発明は、円筒空間に均一な高磁場を
供給する強磁場発生手段と、該円筒空間内の半径方向に
傾斜磁場分布を供給する傾斜磁場発生手段と、該傾斜磁
場発生手段を前記円筒空間内の所定の位置に固定する支
持体とを備えた磁気共鳴イメージング装置において、前
記傾斜磁場発生手段と前記支持体との間に該支持体の固
有振動モードに対する干渉部材を設けたことを特徴とす
るものである。The present invention further comprises a strong magnetic field generating means for supplying a uniform high magnetic field to the cylindrical space, a gradient magnetic field generating means for supplying a gradient magnetic field distribution in the radial direction within the cylindrical space, and the gradient magnetic field generating means. In a magnetic resonance imaging apparatus including a support body fixed at a predetermined position in the cylindrical space, an interference member for the natural vibration mode of the support body is provided between the gradient magnetic field generating means and the support body. It is characterized by.
【００１２】前記磁気共鳴イメージング装置において、
弾性体は防振ゴム、高分子化合物樹脂、金属であるもの
がよい。また分割部材は支持体よりも半径が大きく且つ
該支持体に密着する円筒を、円筒の軸方向に分割した部
材であるのがよい。また分割部材と支持体との間に減衰
材を配したものがよい。また複数の分割部材がすべて同
一であるもの又は複数の分割部材が不均等分割されたも
のであるのいずれもよい。In the magnetic resonance imaging apparatus,
The elastic body is preferably made of vibration-proof rubber, polymer compound resin, or metal. Further, the dividing member is preferably a member obtained by dividing a cylinder having a radius larger than that of the support and closely contacting the support in the axial direction of the cylinder. Further, it is preferable to dispose a damping material between the dividing member and the support. Further, the plurality of dividing members may all be the same or the plurality of dividing members may be unevenly divided.
【００１３】また、本発明は、円筒空間に均一な高磁場
を供給する強磁場発生手段と、該円筒空間内の半径方向
に傾斜磁場分布を供給する傾斜磁場発生手段と、該傾斜
磁場発生手段を前記円筒空間内の所定の位置に固定する
支持体とを備えて成る磁気共鳴イメージング装置におい
て、該支持体に設けられた軸方向のスリットに減衰材が
充填されたことを特徴とするものである。Further, according to the present invention, a strong magnetic field generating means for supplying a uniform high magnetic field to the cylindrical space, a gradient magnetic field generating means for supplying a gradient magnetic field distribution in the radial direction within the cylindrical space, and the gradient magnetic field generating means. In a magnetic resonance imaging apparatus comprising: a support body for fixing at a predetermined position in the cylindrical space, an axial slit provided in the support body is filled with an attenuating material. is there.
【００１４】[0014]
【作用】この発明において電磁力によって生じる傾斜磁
場コイルのパルス的な荷重は、支持体すなわちボビンと
分割部材とに伝達される。このとき、ボビンと分割部材
とは振動するが、両者が異なる形状をしているため、各
々の固有振動数ならびに発生する固有振動モードが異な
る。かつ、両者が固定部材によって固定されているた
め、両者の間には、各々が発生する固有振動モードを互
いに抑制しようとする挙動すなわち干渉作用が生じる。
このため、上記構造とすることでボビンが単体で存在す
るよりも大きな低振動効果が得られる。そのため、ボビ
ンの振動によって生じる騒音を大幅に低減できる。弾性
体や減衰材の介在は一層の低振動効果を図れる。また支
持体のスリットに減衰材を設けた構造も前記分割部材の
設置とほぼ同様の作用効果が得られる。In the present invention, the pulsed load of the gradient magnetic field coil generated by the electromagnetic force is transmitted to the support, that is, the bobbin and the dividing member. At this time, the bobbin and the dividing member vibrate, but since the two have different shapes, the natural frequency and the natural vibration mode to be generated are different. In addition, since both are fixed by the fixing member, a behavior, that is, an interference action, that mutually suppresses the natural vibration modes generated by each, occurs between the both.
Therefore, with the above-described structure, a larger vibration effect can be obtained than when the bobbin exists alone. Therefore, the noise generated by the vibration of the bobbin can be significantly reduced. The interposition of the elastic body and the damping material can further reduce the vibration effect. Further, the structure in which the damping material is provided in the slit of the support can also obtain substantially the same operational effect as the installation of the dividing member.
【００１５】[0015]
【実施例】以下、本発明の実施例を図面に従って説明す
る。図１は本発明の一実施例に係る磁気共鳴イメージン
グ装置の構造を示す図で、円筒体の側面より手前側の外
筒（シールド部）及びクライオスタット部を除去して内
部の様子を示した図である図２はボビン及び傾斜磁場コ
イルの取付状況を示す図である。内部を真空断熱したク
ライオスタット１内に液体ヘリウム槽２を設け、これに
静磁場発生用の超電導マグネット（磁石）３を内蔵させ
て高磁場発生手段を構成し、超電導マグネット３を液体
ヘリウム４で冷却する。この超電導マグネット３によっ
てクライオスタット１の中央部空間のボア５内軸方向に
０.５〜４テスラの静磁場が発生する。ボア５内には、
静磁場ｚ方向に対して、それぞれｘ方向、ｙ方向、ｚ方
向に傾斜磁場コイル６を配置している。傾斜磁場コイル
６はｘ方向、傾斜磁場コイル７はｙ方向コイルである。
なお、頻雑さを避けるため、ｚ方向コイルについては図
示していない。Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the structure of a magnetic resonance imaging apparatus according to an embodiment of the present invention, showing an internal state with the outer cylinder (shield portion) and the cryostat portion on the front side of the side surface of the cylindrical body removed. FIG. 2 is a view showing a mounting state of the bobbin and the gradient magnetic field coil. A liquid helium tank 2 is provided in a cryostat 1 whose interior is vacuum-insulated, and a superconducting magnet (magnet) 3 for generating a static magnetic field is built in the cryostat 1 to form a high magnetic field generating means, and the superconducting magnet 3 is cooled with liquid helium 4. To do. The superconducting magnet 3 generates a static magnetic field of 0.5 to 4 Tesla in the axial direction of the bore 5 in the central space of the cryostat 1. In bore 5,
The gradient magnetic field coils 6 are arranged in the x direction, the y direction, and the z direction with respect to the static magnetic field z direction. The gradient magnetic field coil 6 is an x-direction coil, and the gradient magnetic field coil 7 is a y-direction coil.
Note that the z-direction coil is not shown in order to avoid complexity.
【００１６】ボビン１０の外側には、複数の分割部材８
が配置され、両者はバンド１３によって強固に固定され
ている。傾斜磁場コイルは締結金具１５，１６により締
結し、一体化されており、剛性は非常に高く、複数の弾
性体９ならびに分割部材８を介して、ボビン１０で支持
される。分割部材は非磁性体であればよく例えばＦＲＰ
等である。弾性体９は防振ゴム、高分子化合物樹脂又は
金属などで形成されている。また、分割部材８はボビン
１０よりも半径が大きく且つボビン１０に密着する円筒
を、円筒の軸方向に平行に分割されている。ボビン１０
の両端部は、支持ボルト１１によってクライオスタット
１の内面で支持されており、これによって、鞍形の傾斜
磁場コイル６および７の位置合せ（すなわち円筒体の軸
芯合わせ）を行う。また、クライオスタット１の外側に
は、漏洩磁場空間域を小さく抑えるため、重量が数トン
の鉄製の磁気シールド体１２を設けている。Outside the bobbin 10, a plurality of dividing members 8 are provided.
Are arranged, and both are firmly fixed by the band 13. The gradient magnetic field coil is fastened by fasteners 15 and 16 and integrated, and has a very high rigidity, and is supported by the bobbin 10 through the plurality of elastic bodies 9 and the dividing member 8. The dividing member may be a non-magnetic material, such as FRP.
Etc. The elastic body 9 is formed of vibration-proof rubber, polymer compound resin, metal, or the like. Further, the dividing member 8 has a radius larger than that of the bobbin 10 and a cylinder that is in close contact with the bobbin 10 is divided parallel to the axial direction of the cylinder. Bobbin 10
Both end portions of are supported by the inner surface of the cryostat 1 by the support bolts 11, and thereby the saddle-shaped gradient magnetic field coils 6 and 7 are aligned (that is, the axial center of the cylindrical body is aligned). Further, on the outside of the cryostat 1, a magnetic shield body 12 made of iron and having a weight of several tons is provided in order to keep the leakage magnetic field space region small.
【００１７】ここで鞍形の傾斜磁場コイル７に傾斜磁場
発生用のパルス電流ｉを流す場合を考える。コイルの円
周部に作用する電磁力は、フレミングの左手の法則に従
い、静磁場方向が図１中の左から右方向にあるとき、左
端上側コイル円周部には半径方向外側に、同下側のコイ
ル円周部には半径方向軸中心向きに作用する。またコイ
ル７の左側中央部の円周部には電流が逆向きに流れるの
で、これと逆向きの荷重が作用する。なお、コイル６に
ついても電流が流れるのでこれと同様な力が働く。以上
述べた電磁力は鞍形コイル６および７を変形させようと
するものであり、もしコイル６および７が変形するなら
ば傾斜磁場に歪が生じて画像処理精度が低下することに
なる。しかし本例においては、傾斜磁場コイル６および
７は強固に連結され、剛性も大きくなっているので、こ
の荷重による傾斜磁場コイル６および７の変形は拘束さ
れ、その変位量を非常に小さくすることができる。傾斜
磁場コイル６および７にかかる荷重は弾性体９に伝わる
が、多数個の弾性体９に分散するため、単位面積当りの
荷重は小さい。したがって、弾性体９の変位量は十分小
さく、傾斜磁場分布に乱れを生じさせることなく、その
結果、３次元空間で高画質の画像を得ることができる。Here, consider a case where a pulse current i for generating a gradient magnetic field is passed through the saddle-shaped gradient magnetic field coil 7. According to Fleming's left-hand rule, when the static magnetic field direction is from the left to the right in FIG. 1, the electromagnetic force acting on the circumferential part of the coil is radially outward from the left end upper coil circumferential part, and The coil circumferential portion on the side acts in the radial axial direction. Further, since the current flows in the opposite direction to the circumferential portion of the coil 7 on the left side central portion, a load in the opposite direction acts on the current. Since a current also flows through the coil 6, a force similar to this works. The electromagnetic force described above is intended to deform the saddle coils 6 and 7, and if the coils 6 and 7 are deformed, the gradient magnetic field is distorted and the image processing accuracy is deteriorated. However, in this example, since the gradient magnetic field coils 6 and 7 are strongly connected and the rigidity is also high, the deformation of the gradient magnetic field coils 6 and 7 due to this load is restricted, and the displacement amount thereof should be extremely small. You can Although the load applied to the gradient magnetic field coils 6 and 7 is transmitted to the elastic body 9, the load per unit area is small because the load is distributed to the large number of elastic bodies 9. Therefore, the displacement amount of the elastic body 9 is sufficiently small, and the gradient magnetic field distribution is not disturbed. As a result, a high-quality image can be obtained in the three-dimensional space.
【００１８】しかし、近年、磁気共鳴イメージング装置
では高磁場化傾向が進み、先に述べた電磁力が大きくな
ってきているため、上記弾性体９だけでは該装置の大幅
な低騒音化が困難である。そこで、ボビン自身の低振動
化が不可欠である。本例では、ボビン１０の外側にバン
ド１３によって強固に固定された分割部材８がボビン１
０の低振動化に寄与している。以下、分割部材８の働き
について説明する。ボビン１０の概略形状は図３に示す
ような円筒である。本ボビン１０を図中のＡ−Ａ方向か
ら見た場合、図４及び図５で代表される固有振動モード
が生じる。つまり、一点鎖線が円筒断面の原形を表わ
し、その固有振動モードが実線で表示されている。分割
部材８がない場合には、コイルの振動が弾性体９を介し
てボビン１０に伝わり、該振動モードを励起する。この
ように発生したボビン１０の振動はなかなか減衰せず、
ボビン１０の内外に大きな騒音を発生させることとな
る。分割部材８が本ボビン１０に付加されると、それら
両者の固有振動数ならびに固有振動モードが異なるため
に、お互いにそれぞれの固有振動モードの発生を抑制し
ようとする。すなわち干渉しあう。従って、ボビン１０
の振動が分割部材８によって低減されることになる。よ
って、本実施例では磁気共鳴イメージング装置の大きな
低騒音化が図れる。尚、上記実施例では、分割部材８と
してボビン１０よりも一回り大きな円筒を２分割したも
のを用いているが、図６に示した如く分割数を増やした
ものであってもかまわない。また、図７に示した如く分
割は均等である必要はない。また、図８に示した如くボ
ビン１０と分割部材８との間に減衰材２５を挿入しても
よい。また、図９に示すように分割部材８はボビン１０
の内側に突っ張り部材２４等を用いて固定してもよい。
なお、このとき分割部材８はボビン１０よりも１回り小
さな円筒を軸方向に分割したものである。However, in recent years, in the magnetic resonance imaging apparatus, the tendency to increase the magnetic field has progressed, and the electromagnetic force described above has increased. Therefore, it is difficult to significantly reduce the noise of the apparatus only with the elastic body 9. is there. Therefore, it is essential to reduce the vibration of the bobbin itself. In this example, the split member 8 that is firmly fixed to the outside of the bobbin 10 by the band 13 is the bobbin 1.
This contributes to a low vibration of 0. Hereinafter, the function of the dividing member 8 will be described. The general shape of the bobbin 10 is a cylinder as shown in FIG. When the bobbin 10 is viewed from the AA direction in the drawing, a natural vibration mode represented by FIGS. 4 and 5 occurs. That is, the alternate long and short dash line represents the original shape of the cylindrical cross section, and its natural vibration mode is shown by the solid line. When the dividing member 8 is not provided, the vibration of the coil is transmitted to the bobbin 10 via the elastic body 9 to excite the vibration mode. The vibration of the bobbin 10 thus generated is not easily attenuated,
Large noise is generated inside and outside the bobbin 10. When the dividing member 8 is added to the bobbin 10, since the natural frequencies and the natural vibration modes of the both are different, they try to suppress the occurrence of the respective natural vibration modes. That is, they interfere with each other. Therefore, bobbin 10
Will be reduced by the dividing member 8. Therefore, in this embodiment, the noise of the magnetic resonance imaging apparatus can be greatly reduced. In addition, in the above-mentioned embodiment, a cylinder which is slightly larger than the bobbin 10 is divided into two as the dividing member 8, but the number of divisions may be increased as shown in FIG. Further, as shown in FIG. 7, the division need not be even. Further, as shown in FIG. 8, a damping member 25 may be inserted between the bobbin 10 and the dividing member 8. In addition, as shown in FIG.
You may fix it using the bracing member 24 etc. inside.
At this time, the dividing member 8 is formed by axially dividing a cylinder that is smaller than the bobbin 10 by one size.
【００１９】他の実施例のボビン１０を図１０に示す。
ボビン１０は、２つの分割部材８と両者を結合する減衰
材２５とにより構成されている。すなわち、ここでは、
これまで述べてきた基本となる円筒のボビン１０がな
く、分割部材８がボビン１０の主要部を成す。分割部材
８の振動は、減衰材２５によって減衰されるので、ボビ
ン１０の低振動化が図れる。これによって磁気共鳴イメ
ージング装置の低騒音化が可能となる。なお、本実施例
においても前述したと同様に分割数を増してもよい（図
１１）。また、分割は均等である必要はない（図１
２）。また、減衰材２５によって分割部材８が十分強固
に結合できなくてボビン１０としての剛性が十分でない
場合には図１３に示すように、円筒のボビン１０に軸方
向にスリットを設けそこに減衰材２５を充填する構造と
してもよい。あるいは、剛性増加のために図１０の構造
にリング状部材２６を設けて補強を図ってもよい（図１
４）。A bobbin 10 of another embodiment is shown in FIG.
The bobbin 10 is composed of two divided members 8 and a damping member 25 that connects the two divided members 8. That is, here
There is no basic cylindrical bobbin 10 described so far, and the dividing member 8 constitutes the main part of the bobbin 10. Since the vibration of the split member 8 is damped by the damping material 25, the vibration of the bobbin 10 can be reduced. This makes it possible to reduce the noise of the magnetic resonance imaging apparatus. In the present embodiment as well, the number of divisions may be increased as described above (FIG. 11). Also, the division need not be even (see FIG.
2). Further, when the split member 8 cannot be firmly joined by the damping material 25 and the rigidity of the bobbin 10 is not sufficient, as shown in FIG. 13, a slit is provided in the cylindrical bobbin 10 in the axial direction, and the damping material is provided there. The structure may be such that 25 is filled. Alternatively, in order to increase the rigidity, the structure shown in FIG. 10 may be provided with a ring-shaped member 26 for reinforcement (FIG. 1).
4).
【００２０】[0020]
【発明の効果】本発明によれば、傾斜磁場コイルにパル
ス電流を流した時に生じる電磁力すなわち傾斜磁場コイ
ルに作用する変形荷重を、剛性の大きなコイルで受け、
その変形量を十分小さく抑え込むため、傾斜磁場コイル
の動きによる磁場の乱れが無く、高画質の画像を得られ
る効果がある。一方、コイルからの力によって発生する
ボビンの振動は、分割部材や減衰材によって十分抑制さ
れるので、ボビンの振動によって発生する騒音を低減で
きる効果がある。According to the present invention, the electromagnetic force generated when a pulse current is applied to the gradient magnetic field coil, that is, the deformation load acting on the gradient magnetic field coil is received by the coil having a large rigidity.
Since the amount of deformation is suppressed to a sufficiently small level, there is no disturbance of the magnetic field due to the movement of the gradient magnetic field coil, and there is an effect that a high quality image can be obtained. On the other hand, since the vibration of the bobbin generated by the force from the coil is sufficiently suppressed by the dividing member and the damping material, it is possible to reduce the noise generated by the vibration of the bobbin.
【図１】本発明の一実施例に係る磁気共鳴イメージング
装置の内部構造物の部分断面図である。FIG. 1 is a partial cross-sectional view of an internal structure of a magnetic resonance imaging apparatus according to an embodiment of the present invention.
【図２】図１の実施例装置に適用するボビン及び傾斜磁
場コイルの部分を示す要部断面図である。FIG. 2 is a cross-sectional view of essential parts showing a bobbin and a gradient magnetic field coil portion applied to the apparatus of the embodiment of FIG.
【図３】ボビン円筒体の斜視図である。FIG. 3 is a perspective view of a bobbin cylindrical body.
【図４】図３のボビンの固有振動モード図である。4 is a natural vibration mode diagram of the bobbin of FIG.
【図５】図３のボビンの固有振動モード図である。5 is a natural vibration mode diagram of the bobbin of FIG.
【図６】他の実施例の要部断面図である。FIG. 6 is a cross-sectional view of main parts of another embodiment.
【図７】他の実施例の要部断面図である。FIG. 7 is a cross-sectional view of main parts of another embodiment.
【図８】他の実施例の要部断面図である。FIG. 8 is a cross-sectional view of main parts of another embodiment.
【図９】他の実施例の要部断面図である。FIG. 9 is a cross-sectional view of main parts of another embodiment.
【図１０】他の実施例の要部断面図である。FIG. 10 is a cross-sectional view of main parts of another embodiment.
【図１１】他の実施例の要部断面図である。FIG. 11 is a sectional view of an essential part of another embodiment.
【図１２】他の実施例の要部断面図である。FIG. 12 is a cross-sectional view of main parts of another embodiment.
【図１３】その他の実施例の要部斜視図である。FIG. 13 is a perspective view of a main part of another embodiment.
【図１４】その他の実施例の要部斜視図である。FIG. 14 is a perspective view of a main part of another embodiment.
１ クライオスタット ３ 超電導マグネット ５ ボア ６ 傾斜磁場コイル（ｘ方向） ７ 傾斜磁場コイル（ｙ方向） ８ 分割部材 ９ 弾性体 １０ ボビン ２５ 減衰材 1 Cryostat 3 Superconducting magnet 5 bore 6 Gradient field coil (x direction) 7 Gradient magnetic field coil (y direction) 8 split members 9 elastic body 10 bobbins 25 damping material
───────────────────────────────────────────────────── フロントページの続き (72)発明者 大塚 雅之 茨城県勝田市市毛882番地 株式会社日立 製作所那珂工場内 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Masayuki Otsuka Hitachi, Ltd. 882, Imo, Katsuta-shi, Ibaraki Factory Naka Factory
Claims (11)
場発生手段と、該円筒空間内の半径方向に傾斜磁場分布
を供給する傾斜磁場発生手段と、該傾斜磁場発生手段を
前記円筒空間内の所定の位置に固定する支持体とを備え
た磁気共鳴イメージング装置において、前記傾斜磁場発
生手段と前記支持体との間に該支持体の剛性と同等の分
割部材を設けたことを特徴とする磁気共鳴イメージング
装置。1. A strong magnetic field generating means for supplying a uniform high magnetic field to a cylindrical space, a gradient magnetic field generating means for supplying a gradient magnetic field distribution in a radial direction within the cylindrical space, and the gradient magnetic field generating means for the cylindrical space. In a magnetic resonance imaging apparatus including a support body fixed at a predetermined position inside, a dividing member having rigidity equal to that of the support body is provided between the gradient magnetic field generating means and the support body. Magnetic resonance imaging apparatus.
場発生手段と、該円筒空間内の半径方向に傾斜磁場分布
を供給する傾斜磁場発生手段と、該傾斜磁場発生手段を
前記円筒空間内の所定の位置に固定する支持体とを備え
た磁気共鳴イメージング装置において、前記傾斜磁場発
生手段と前記支持体との間に該支持体よりも剛性の小さ
な弾性体と該支持体の剛性と同等の分割部材とを設けた
ことを特徴とする磁気共鳴イメージング装置。2. A strong magnetic field generating means for supplying a uniform high magnetic field to a cylindrical space, a gradient magnetic field generating means for supplying a gradient magnetic field distribution in a radial direction within the cylindrical space, and the gradient magnetic field generating means for the cylindrical space. In a magnetic resonance imaging apparatus including a support fixed at a predetermined position inside, an elastic body having a rigidity smaller than that of the support and the rigidity of the support between the gradient magnetic field generating means and the support. A magnetic resonance imaging apparatus, which is provided with an equivalent dividing member.
場発生手段と、該円筒空間内の半径方向に傾斜磁場分布
を供給する傾斜磁場発生手段と、該傾斜磁場発生手段を
前記円筒空間内の所定の位置に固定する支持体とを備え
た磁気共鳴イメージング装置において、前記傾斜磁場発
生手段と前記支持体との間に支持体よりも剛性の小さな
弾性体を設け、該支持体の内壁に該支持体の剛性と同等
の分割部材を設けたことを特徴とする磁気共鳴イメージ
ング装置。3. A strong magnetic field generating means for supplying a uniform high magnetic field to the cylindrical space, a gradient magnetic field generating means for supplying a gradient magnetic field distribution in the radial direction within the cylindrical space, and the gradient magnetic field generating means for the cylindrical space. In a magnetic resonance imaging apparatus including a support body fixed at a predetermined position inside, an elastic body having a rigidity smaller than that of the support body is provided between the gradient magnetic field generating means and the support body, and an inner wall of the support body A magnetic resonance imaging apparatus characterized in that a dividing member having a rigidity equal to that of the support is provided on the.
場発生手段と、該円筒空間内の半径方向に傾斜磁場分布
を供給する傾斜磁場発生手段と、該傾斜磁場発生手段を
前記円筒空間内の所定の位置に固定する支持体とを備え
た磁気共鳴イメージング装置において、該支持体が円筒
を分割した複数の分割部材と該分割部材を連結する減衰
材とより成ることを特徴とする磁気共鳴イメージング装
置。4. A strong magnetic field generating means for supplying a uniform high magnetic field to a cylindrical space, a gradient magnetic field generating means for supplying a gradient magnetic field distribution in the radial direction in the cylindrical space, and the gradient magnetic field generating means for the cylindrical space. In a magnetic resonance imaging apparatus provided with a support body fixed at a predetermined position in the inside, the support body is composed of a plurality of division members that divide a cylinder and an attenuation material that connects the division members. Resonance imaging device.
場発生手段と、該円筒空間内の半径方向に傾斜磁場分布
を供給する傾斜磁場発生手段と、該傾斜磁場発生手段を
前記円筒空間内の所定の位置に固定する支持体とを備え
た磁気共鳴イメージング装置において、前記傾斜磁場発
生手段と前記支持体との間に該支持体の固有振動モード
に対する干渉部材を設けたことを特徴とする磁気共鳴イ
メージング装置。5. A strong magnetic field generating means for supplying a uniform high magnetic field to a cylindrical space, a gradient magnetic field generating means for supplying a gradient magnetic field distribution in the radial direction within the cylindrical space, and the gradient magnetic field generating means for supplying the gradient magnetic field generating means to the cylindrical space. In a magnetic resonance imaging apparatus having a support fixed at a predetermined position inside, an interference member for the natural vibration mode of the support is provided between the gradient magnetic field generating means and the support. Magnetic resonance imaging apparatus.
高分子化合物樹脂、金属であることを特徴とする磁気共
鳴イメージング装置。6. The elastic body according to claim 2, wherein the elastic body is a vibration-proof rubber,
A magnetic resonance imaging apparatus comprising a polymer compound resin and a metal.
部材は支持体よりも半径が大きく且つ該支持体に密着す
る円筒を、円筒の軸方向に分割した部材であることを特
徴とする磁気共鳴イメージング装置。7. The split member according to claim 1, wherein the split member is a member that has a radius larger than that of the support and is in close contact with the support, and that is split in the axial direction of the cylinder. Magnetic resonance imaging system.
部材と支持体との間に減衰材を配したことを特徴とする
磁気共鳴イメージング装置。8. A magnetic resonance imaging apparatus according to claim 1, wherein a damping material is arranged between the dividing member and the support.
の分割部材がすべて同一であることを特徴とする磁気共
鳴イメージング装置。9. The magnetic resonance imaging apparatus according to claim 1, wherein the plurality of division members are all the same.
数の分割部材が不均等分割されたものであることを特徴
とする磁気共鳴イメージング装置。10. The magnetic resonance imaging apparatus according to claim 1, wherein the plurality of dividing members are non-uniformly divided.
磁場発生手段と、該円筒空間内の半径方向に傾斜磁場分
布を供給する傾斜磁場発生手段と、該傾斜磁場発生手段
を前記円筒空間内の所定の位置に固定する支持体とを備
えて成る磁気共鳴イメージング装置において、該支持体
に設けられた軸方向のスリットに減衰材が充填されたこ
とを特徴とする磁気共鳴イメージング装置。11. A strong magnetic field generating means for supplying a uniform high magnetic field to a cylindrical space, a gradient magnetic field generating means for supplying a gradient magnetic field distribution in a radial direction within the cylindrical space, and the gradient magnetic field generating means for the cylindrical space. A magnetic resonance imaging apparatus comprising a support body fixed at a predetermined position inside the magnetic resonance imaging apparatus, wherein an axial slit provided in the support body is filled with an attenuating material.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15177291A JP3156088B2 (en) | 1991-06-24 | 1991-06-24 | Magnetic resonance imaging equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15177291A JP3156088B2 (en) | 1991-06-24 | 1991-06-24 | Magnetic resonance imaging equipment |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05132A true JPH05132A (en) | 1993-01-08 |
| JP3156088B2 JP3156088B2 (en) | 2001-04-16 |
Family
ID=15525960
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP15177291A Expired - Fee Related JP3156088B2 (en) | 1991-06-24 | 1991-06-24 | Magnetic resonance imaging equipment |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3156088B2 (en) |
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| WO2001016616A3 (en) * | 1999-08-27 | 2001-07-26 | Peter Mansfield | Active acoustic control for gradient coil structures in mri |
| JP2002085378A (en) * | 2000-09-20 | 2002-03-26 | Toshiba Medical System Co Ltd | RF coil used for magnetic resonance imaging apparatus |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3341306B2 (en) | 1992-08-06 | 2002-11-05 | 株式会社日立製作所 | Gradient magnetic field coil and nuclear magnetic resonance imaging apparatus using the same |
| WO2005115239A1 (en) | 2004-05-31 | 2005-12-08 | Hitachi Medical Corporation | Magnetic resonance imaging device |
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1991
- 1991-06-24 JP JP15177291A patent/JP3156088B2/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001016616A3 (en) * | 1999-08-27 | 2001-07-26 | Peter Mansfield | Active acoustic control for gradient coil structures in mri |
| JP2001192714A (en) * | 2000-01-12 | 2001-07-17 | Kobe Steel Ltd | Method for charging raw material to blast furnace |
| JP2002085378A (en) * | 2000-09-20 | 2002-03-26 | Toshiba Medical System Co Ltd | RF coil used for magnetic resonance imaging apparatus |
| GB2382145A (en) * | 2001-07-23 | 2003-05-21 | Siemens Ag | Nmr tomography machine having damping laminated sheets for reducing vibrations |
| US6831461B2 (en) | 2001-07-23 | 2004-12-14 | Siemens Aktiengesellschaft | Magnetic resonance tomography apparatus having damping laminated sheets for reducing vibrations |
| GB2382145B (en) * | 2001-07-23 | 2005-10-19 | Siemens Ag | NMR tomograhphy machine having damping laminated sheets for reducing vibrations |
| US9205007B2 (en) | 2010-11-10 | 2015-12-08 | Ferno-Washington, Inc. | Life support litter having a plurality of vibration dampers |
| JP2020204379A (en) * | 2019-06-18 | 2020-12-24 | 株式会社東芝 | Vibration suppression device of structure, and superconducting magnet device |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3156088B2 (en) | 2001-04-16 |
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