JPH04341238A - Gradient magnetic field generating device - Google Patents
Gradient magnetic field generating deviceInfo
- Publication number
- JPH04341238A JPH04341238A JP3140909A JP14090991A JPH04341238A JP H04341238 A JPH04341238 A JP H04341238A JP 3140909 A JP3140909 A JP 3140909A JP 14090991 A JP14090991 A JP 14090991A JP H04341238 A JPH04341238 A JP H04341238A
- Authority
- JP
- Japan
- Prior art keywords
- magnetic field
- gradient magnetic
- coils
- gradient
- origin
- 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
- 230000003068 static effect Effects 0.000 claims abstract description 6
- 239000002131 composite material Substances 0.000 abstract description 2
- 230000002194 synthesizing effect Effects 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 3
- 238000002595 magnetic resonance imaging Methods 0.000 description 2
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000002123 temporal effect Effects 0.000 description 1
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- Magnetic Resonance Imaging Apparatus (AREA)
Abstract
Description
【０００１】0001
【産業上の利用分野】本発明は、磁気共鳴映像装置など
で用いられる勾配磁界発生装置に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gradient magnetic field generating device used in magnetic resonance imaging devices and the like.
【０００２】0002
【従来の技術】磁気共鳴映像装置においては、磁界勾配
を印加して測定を行っている。この磁界勾配は、Ｘ，Ｙ
，Ｚの各方向個別の勾配磁界成分を、第２図に示すよう
に各方向に個別に設けたコイルによって発生させていた
。2. Description of the Related Art In a magnetic resonance imaging apparatus, measurements are performed by applying a magnetic field gradient. This magnetic field gradient is
, Z are generated by separate coils provided in each direction as shown in FIG.
【０００３】0003
【発明が解決しようとする課題】この様な勾配コイルで
は、単純なコイル構成による近似のため、生成される勾
配磁界のリニアリティが悪く（高次の歪みを持つ）、映
像に歪みが発生してしまう。また、その高次の歪み成分
により、磁界均一度調整用のシムコイルや静磁界を発生
するコイルとの相互結合が生ずるため、勾配磁界をパル
ス的に発生する際に時間的応答が劣悪になるという問題
もある。[Problem to be Solved by the Invention] In such a gradient coil, since the approximation is based on a simple coil configuration, the linearity of the generated gradient magnetic field is poor (it has high-order distortion), and distortion occurs in the image. Put it away. In addition, the high-order distortion components cause mutual coupling with the shim coil for magnetic field uniformity adjustment and the coil that generates the static magnetic field, resulting in poor temporal response when generating a pulsed gradient magnetic field. There are also problems.
【０００４】本発明は、上述した諸点に鑑みてなされた
ものであり、リニアリティの高い勾配磁界を発生するこ
とができる勾配磁界発生装置を提供することを目的とし
ている。The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a gradient magnetic field generating device capable of generating a gradient magnetic field with high linearity.
【０００５】[0005]
【課題を解決するための手段】この目的を達成するため
、本発明は、静磁場の中心を通る軸に沿い、該中心を挟
んで対称に配置され且つ互いに逆向きの磁界を発生させ
るコイル対を中心からの距離を異ならせて複数対配置す
ると共に、各コイル対に独立に電流を供給するために各
コイル対ごとに設けられた電源と、各コイル対ごとに予
め定められた比率の電流を供給するように複数の電源を
制御する制御手段とを備えたことを特徴としている。[Means for Solving the Problems] In order to achieve this object, the present invention provides a pair of coils arranged symmetrically across the center of a static magnetic field along an axis passing through the center of the static magnetic field and generating magnetic fields in opposite directions. A plurality of pairs of coils are arranged at different distances from the center, and a power source is provided for each coil pair to independently supply current to each coil pair, and a current at a predetermined ratio for each coil pair. The present invention is characterized by comprising a control means for controlling a plurality of power sources so as to supply the power.
【０００６】[0006]
【作用】各コイル対に供給する電流強度及びその配分を
適宜設定することにより、任意の分布の勾配磁界を発生
することができ、従って、リニアリティの良好な勾配磁
界を発生することができる。[Operation] By appropriately setting the current intensity supplied to each coil pair and its distribution, a gradient magnetic field with an arbitrary distribution can be generated, and therefore a gradient magnetic field with good linearity can be generated.
【０００７】[0007]
【実施例】以下、図面に基づいて本発明の一実施例を詳
説する。図１は本発明の一実施例を示すブロック図であ
り、図においてコイル対（Ｌ１ａ，Ｌ１ｂ）はＺ軸（静
磁界方向）上に同軸的に且つ原点Ｏを挟んで対称に配置
される。異なった位置にその他のコイル対（Ｌ２ａ，Ｌ
２ｂ）・・・（Ｌｎａ，Ｌｎｂ）が同様に配置されてい
る。DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention, and in the figure, a coil pair (L1a, L1b) is arranged coaxially on the Z axis (static magnetic field direction) and symmetrically with respect to the origin O. Other coil pairs (L2a, L
2b)...(Lna, Lnb) are similarly arranged.
【０００８】Ｐ１ａ，Ｐ１ｂは、コイル対（Ｌ１ａ，Ｌ
１ｂ）へそれぞれ電流Ｉ１ａ，Ｉ１ｂを供給するための
電源であり、その他の各コイル対（Ｌ２ａ，Ｌ２ｂ）・
・・（Ｌｎａ，Ｌｎｂ）にも、電源（Ｐ２ａ，Ｐ２ｂ）
・・・（Ｐｎａ，Ｐｎｂ）からそれぞれ（Ｉ２ａ，Ｉ２
ｂ）・・・（Ｉｎａ，Ｉｎｂ）が供給される。各電源に
は、中央制御装置１から各コイルへ供給する電流を指定
する指令信号が送られる。P1a and P1b are a coil pair (L1a, L
1b), respectively, and is a power source for supplying currents I1a and I1b to each of the other coil pairs (L2a, L2b) and
... (Lna, Lnb) also has power supply (P2a, P2b)
...(Pna, Pnb) respectively (I2a, I2
b)...(Ina, Inb) is supplied. A command signal specifying the current to be supplied to each coil is sent from the central control device 1 to each power source.
【０００９】上記構成において、コイルＬ１ａとコイル
Ｌ１ｂに供給される電流Ｉ１ａ，Ｉ１ｂは、値が等しく
流れる方向が逆であり、コイルＬ１ａとコイルＬ１ｂと
は強度が等しく逆向きの磁界を発生する。その結果、原
点Ｏ付近には２つのコイルＬ１ａ，コイルＬ１ｂによる
勾配磁界が発生する。全く同様に、原点付近には異なっ
た位置に配置されるその他のコイル対により異なった勾
配磁界が発生し、そのため原点付近の勾配磁界はそれら
の勾配磁界が合成されたものとなる。従って、各コイル
対に供給する電流の値（比率）を適宜設定すれば、任意
の勾配を持った合成勾配磁界を発生させることができる
。In the above configuration, the currents I1a and I1b supplied to the coils L1a and L1b have equal values and flow in opposite directions, and the coils L1a and L1b generate magnetic fields having equal strengths and opposite directions. As a result, a gradient magnetic field is generated near the origin O by the two coils L1a and L1b. In exactly the same way, different gradient magnetic fields are generated near the origin by other coil pairs arranged at different positions, so that the gradient magnetic field near the origin is a combination of these gradient magnetic fields. Therefore, by appropriately setting the value (ratio) of the current supplied to each coil pair, a composite gradient magnetic field having an arbitrary gradient can be generated.
【００１０】尚、各コイル対の配置は任意で良く、等間
隔でも原点からの距離に応じてその間隔を変えるように
しても良い。図２に示すようにすべてのコイルが等間隔
に配置されている場合には、対をとなるコイルに等しい
電流を供給するのではなく、例えばＩｎａ＞Ｉｎｂ，Ｉ
ｎ−１ａ＞Ｉｎ−１ｂ・・・あるいはＩｎａ＜Ｉｎｂ，
Ｉｎ−１ａ＜Ｉｎ−１ｂ・・・とすることにより、勾配
磁界の傾斜中心を図１の上側あるいは下側へシフトする
ことができる。[0010] The arrangement of each coil pair may be arbitrary, and the spacing may be evenly spaced or may be varied depending on the distance from the origin. If all the coils are equally spaced as shown in Figure 2, instead of supplying equal current to the coils in the pair, for example
n-1a>In-1b...or Ina<Inb,
By setting In-1a<In-1b..., the center of gradient of the gradient magnetic field can be shifted upward or downward in FIG.
【００１１】また、原点からの距離に応じてコイル対の
間隔を適宜設定することにより、中心部分における傾斜
磁界の分布精度を高めることが可能である。Furthermore, by appropriately setting the interval between the coil pairs depending on the distance from the origin, it is possible to improve the distribution accuracy of the gradient magnetic field in the central portion.
【００１２】0012
【発明の効果】以上詳述した如く、本発明によれば、リ
ニアリティの高い勾配磁界を発生することができる勾配
磁界発生装置が実現される。As described in detail above, according to the present invention, a gradient magnetic field generating device capable of generating a gradient magnetic field with high linearity is realized.
【図１】 本発明の一実施例を示す図である。FIG. 1 is a diagram showing an embodiment of the present invention.
【図２】 従来の勾配コイルを示す概略図である。FIG. 2 is a schematic diagram showing a conventional gradient coil.
Ｌ１ａ，Ｌ１ｂ、Ｌ２ａ，Ｌ２ｂ、・・・Ｌｎａ，Ｌｎ
ｂ：コイル対Ｐ１ａ，Ｐ１ｂ、Ｐ２ａ，Ｐ２ｂ、・・・
Ｐｎａ，Ｐｎｂ：電源１：中央制御装置L1a, L1b, L2a, L2b, ... Lna, Ln
b: Coil pairs P1a, P1b, P2a, P2b,...
Pna, Pnb: Power supply 1: Central control unit
Claims (1)
んで対称に配置され且つ互いに逆向きの磁界を発生させ
るコイル対を中心からの距離を異ならせて複数対配置す
ると共に、各コイル対に独立に電流を供給するために各
コイル対ごとに設けられた電源と、各コイル対ごとに予
め定められた比率の電流を供給するように複数の電源を
制御する制御手段とを備えたことを特徴とする勾配磁界
発生装置。Claim 1: A plurality of pairs of coils are arranged symmetrically across the center along an axis passing through the center of the static magnetic field and generate mutually opposite magnetic fields at different distances from the center, and A power supply provided for each coil pair to independently supply current to each coil pair, and a control means for controlling the plurality of power supplies so as to supply a predetermined ratio of current to each coil pair. A gradient magnetic field generator characterized by comprising:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3140909A JPH04341238A (en) | 1991-05-16 | 1991-05-16 | Gradient magnetic field generating device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3140909A JPH04341238A (en) | 1991-05-16 | 1991-05-16 | Gradient magnetic field generating device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH04341238A true JPH04341238A (en) | 1992-11-27 |
Family
ID=15279639
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3140909A Pending JPH04341238A (en) | 1991-05-16 | 1991-05-16 | Gradient magnetic field generating device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH04341238A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103885009A (en) * | 2014-03-13 | 2014-06-25 | 中国计量科学研究院 | Permanent magnet temperature coefficient open-circuit measuring device and method |
-
1991
- 1991-05-16 JP JP3140909A patent/JPH04341238A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103885009A (en) * | 2014-03-13 | 2014-06-25 | 中国计量科学研究院 | Permanent magnet temperature coefficient open-circuit measuring device and method |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A02 | Decision of refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A02 Effective date: 20010327 |