JPS63271910A - Gradient magnetic field generating device for mri - Google Patents
Gradient magnetic field generating device for mriInfo
- Publication number
- JPS63271910A JPS63271910A JP62107560A JP10756087A JPS63271910A JP S63271910 A JPS63271910 A JP S63271910A JP 62107560 A JP62107560 A JP 62107560A JP 10756087 A JP10756087 A JP 10756087A JP S63271910 A JPS63271910 A JP S63271910A
- Authority
- JP
- Japan
- Prior art keywords
- magnetic field
- gradient magnetic
- coil
- rise time
- generating
- 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
- 238000002595 magnetic resonance imaging Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 4
- 230000003068 static effect Effects 0.000 description 3
- 238000003384 imaging method Methods 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
Landscapes
- Magnetic Resonance Imaging Apparatus (AREA)
Abstract
Description
【発明の詳細な説明】
［発明の目的］
（産業上の利用分野）
本発明は、磁気共鳴（Ｍ Ｒ： ｍａｏｎｅｔｉｃ ｒ
ｅＳＯ−ｎａｎｃｅ ）現象を用いて被検体（通常は患
者）のＭＲ像を得る磁気共鳴イメージング（ＭＲＩ）装
置に具陥されるＭＲＩ用傾斜磁場発生装置に関する。[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to magnetic resonance (MR)
The present invention relates to an MRI gradient magnetic field generator incorporated in a magnetic resonance imaging (MRI) apparatus that obtains an MR image of a subject (usually a patient) using the eSO-nance phenomenon.
（従来の技術）
ＭＨＩ装置は、被検体の所望部位に一様な静磁場を印加
し、この静磁場と直角方向にＲＦ磁場を形成する送信用
ＲＦコイルによって、断層像を得る特定のスライス部分
のみに磁気共鳴現象を生じさせ、ざらにＲＦ磁場の解除
侵に原子核から発生する磁気共ｐｊ！信＠（以下ＭＲ倍
信号称する）を受信用ＲＦコイ／Ｌ、−によって検出す
るようにしたもので、静磁場にＸ′軸方向（Ｘ軸からθ
°回転した座標系）に対して直線的な傾斜を持つ線型磁
場勾配を作用させて合成ＭＲ倍信号得、この信号をフー
リエ変換することによりＭＲ低信号周波数とその位相と
に分解して被検体位置情報を得るようにしている。(Prior art) An MHI device applies a uniform static magnetic field to a desired part of a subject, and uses a transmitting RF coil to form an RF magnetic field in a direction perpendicular to the static magnetic field to obtain a tomographic image of a specific slice part. The magnetic resonance phenomenon occurs only when the RF magnetic field is released, and the magnetic resonance generated from the atomic nucleus pj! The signal @ (hereinafter referred to as MR multiplied signal) is detected by the receiving RF coil/L, -, and the static magnetic field is applied in the X'-axis direction (θ from the
A linear magnetic field gradient with a linear gradient is applied to the (rotated coordinate system) to obtain a composite MR multiplied signal, and this signal is Fourier transformed to decompose it into the MR low signal frequency and its phase. I'm trying to get location information.
第２図は従来のＭＲＩ装置に具備される傾斜磁場発生装
置の回路図である。同図に示すように傾斜磁場発生装置
は、直交３軸におけるＸ方向の傾斜磁場を発生するＸ方
向傾斜磁場コイル１ａ。FIG. 2 is a circuit diagram of a gradient magnetic field generator included in a conventional MRI apparatus. As shown in the figure, the gradient magnetic field generator includes an X-direction gradient magnetic field coil 1a that generates a gradient magnetic field in the X-direction in three orthogonal axes.
’ｌｔ）、１Ｃ，１ｄと、Ｙ方向の傾斜磁場を発生する
Ｙ方向傾斜磁場コイル２ａ、２ｂ、２ｃ、２ｄと、Ｚ方
向の傾斜磁場を発生するＺ方向傾斜磁場コイル３ａ、３
ｂと、傾斜磁場発生用の電源たるアンプ４．５．６を有
して成る。'lt), 1C, 1d, Y-direction gradient magnetic field coils 2a, 2b, 2c, 2d that generate a Y-direction gradient magnetic field, and Z-direction gradient magnetic field coils 3a, 3 that generate a Z-direction gradient magnetic field.
b, and an amplifier 4.5.6 serving as a power source for generating a gradient magnetic field.
Ｘ方向及びＹ方向傾斜磁場コイル１ａ乃至１ｄ及び２ａ
乃至２ｄには所謂くら型コイルが適用され、Ｚ方向傾斜
磁場コイル３ａ、３ｂにはソレノイド型コイルが適用さ
れている。しかしてＸ方向傾斜磁場コイル１ａ乃至１ｄ
、Ｙ方向傾斜磁場コイル２ａ乃至２ｄ、Ｚ方向傾斜磁場
コイル３ａ及び３ｂはそれぞれ直列接続され、対応する
アンプ４．５．６より磁場形成用電流が供給されるよう
になっている。第３図はこの電流波形を示している。X-direction and Y-direction gradient magnetic field coils 1a to 1d and 2a
So-called saddle-shaped coils are applied to the coils 2d to 2d, and solenoid-type coils are applied to the Z-direction gradient magnetic field coils 3a and 3b. Therefore, the X-direction gradient magnetic field coils 1a to 1d
, the Y-direction gradient magnetic field coils 2a to 2d, and the Z-direction gradient magnetic field coils 3a and 3b are connected in series, respectively, and a magnetic field forming current is supplied from the corresponding amplifier 4.5.6. FIG. 3 shows this current waveform.
ところで、傾斜磁場はパルス状に印加され、電源の出力
電流（パルスの波高値）と立上り時間。By the way, the gradient magnetic field is applied in the form of pulses, and the output current of the power supply (peak value of the pulse) and rise time.
電源の出力電圧の間には次式の関係がある。There is a relationship between the output voltages of power supplies as shown in the following equation.
Ｖ：出力電圧
Ｌ：コイルのインダクタンス
■：出力電流
ｔｒ：立上り時間
ｒ：コイル抵抗弁
従って、出力電流の増加及び立上り時間の高速化のため
には、高い出力電圧が必要である。V: Output voltage L: Coil inductance ■: Output current tr: Rise time r: Coil resistance valve Therefore, in order to increase the output current and speed up the rise time, a high output voltage is required.
（発明が解決しようとする問題点）
ところで、傾斜ｔａ場を変化させて短時間のうちに複数
のＭＲ倍信号エコー信号）を収集するものとして超高速
イメージングが知られているが、このようなイメージン
グを実行する場合には、傾斜磁場の立上り時間の高速化
が極めて重要となる。(Problems to be Solved by the Invention) By the way, ultrahigh-speed imaging is known as a method of collecting multiple MR multiplexed signals (echo signals) in a short time by changing the gradient ta field. When performing imaging, it is extremely important to increase the rise time of the gradient magnetic field.
傾斜磁場の立上り時間ｔｒの高速化を図るには、上記の
ようにアンプ４．５，６．の出力電圧を高めればよいが
、この出力電圧は最終段の半導体の耐圧等で制限され、
通常５００１Ｖ］以下であるため、傾斜磁場の立上り時
間ｔｒの高速化が困難となっているのが実情である。In order to speed up the rise time tr of the gradient magnetic field, the amplifiers 4.5, 6. However, this output voltage is limited by the breakdown voltage of the final stage semiconductor, etc.
The actual situation is that it is difficult to increase the rise time tr of the gradient magnetic field because the voltage is normally 5001 V] or less.
そこで本発明は上記の欠点を除去するもので、傾斜磁場
の立上り時間の高速化を図ったＭＲＩ用傾斜磁場発生装
置の提供を目的としている。SUMMARY OF THE INVENTION The present invention aims to eliminate the above-mentioned drawbacks and to provide a gradient magnetic field generator for MRI in which the rise time of a gradient magnetic field is increased.
［発明の構成］
（問題点を解決するための手段）
本発明は、直交３軸における各軸方向の傾斜磁場発生用
としてそれぞれ複数のコイルを配置して成るＭＲＩ用傾
斜磁場発生装置において、上記各コイルに対応して複数
の電源を備え、各コイル毎に単独の電源より傾斜磁場発
生用の電流を供給するようにしたものである。[Structure of the Invention] (Means for Solving the Problems) The present invention provides an MRI gradient magnetic field generation device in which a plurality of coils are arranged for generating gradient magnetic fields in each axis direction in three orthogonal axes. A plurality of power supplies are provided corresponding to each coil, and a current for generating a gradient magnetic field is supplied from a single power supply to each coil.
（作 用）
上記構成によれば、一つの電源から見た負荷（コイル）
のインピーダンスが低下し、これにより従来と同じ出力
電圧であるにもかかわらず、傾斜磁場の立上り時間の高
速化を図ることができる。(Function) According to the above configuration, the load (coil) seen from one power source
As a result, the rise time of the gradient magnetic field can be increased even though the output voltage is the same as in the conventional case.
（実施例） 以下、本発明を実施例により具体的に説明する。(Example) Hereinafter, the present invention will be specifically explained with reference to Examples.
第１図は本発明一実施例を示している。FIG. 1 shows one embodiment of the present invention.
同図において２ａ、２ｂ、２ｃ、２ｄばＹ方向の傾斜磁
場を発生するコイルで、それぞれ電源例えばアンプ４ａ
、４ｂ、４ｃ、４ｄの出力端に接続され、各コイル２ａ
乃至２ｄ毎に単独のアンプ４ａ乃至４ｄより傾斜磁場発
生用電流が供給されるようになっている。また、各アン
プ４ａ乃至４ｂの前段にはそれぞれスルーレートリミッ
タ７ａ乃至７ｄが配置されている。このスルーレートリ
ミッタ７ａ乃至７ｄは、各コイル２ａ乃至２ｄ毎の立上
り時間を調整するもので、この調整により、各コイル２
ａ乃至２ｄのインピーダンスのばらつきに起因する立上
り時間差を修正することができる。In the same figure, 2a, 2b, 2c, and 2d are coils that generate gradient magnetic fields in the Y direction, and each has a power source such as an amplifier 4a.
, 4b, 4c, and 4d, and each coil 2a
Gradient magnetic field generation current is supplied from individual amplifiers 4a to 4d every 2d to 2d. Furthermore, slew rate limiters 7a to 7d are arranged in front of each amplifier 4a to 4b, respectively. The slew rate limiters 7a to 7d are for adjusting the rise time of each coil 2a to 2d, and by this adjustment, each coil 2
It is possible to correct the rise time difference caused by variations in impedance from a to 2d.
制御回路８は本実施例装置の動作制御を司るもので、傾
斜磁場の発生タイミング及びその強度等はこの制御回路
８によって制御されるようになっている。The control circuit 8 is responsible for controlling the operation of the apparatus of this embodiment, and the timing of generation of the gradient magnetic field, its intensity, etc. are controlled by the control circuit 8.
以上は、Ｙ方向の傾斜磁場を発生する系のみの説明であ
るが、Ｘ方向及びＺ方向の傾斜磁場を発生する系も上記
と同様に構成され、各コイル１ａ乃至１ｄ及び３ａ、３
ｂ （第２図参照）に対応してアンプ及びスルーレート
リミッタが設けられている。The above is a description of only the system that generates the gradient magnetic field in the Y direction, but the system that generates the gradient magnetic field in the
b (see FIG. 2), an amplifier and a slew rate limiter are provided.
上記構成による実施例装置において、スルーレートリミ
ッタ７ａ乃至７ｄによる立上り時間調整は、各コイル２
ａ乃至２ｄのうち傾斜磁場立上り時間の最も遅いものに
合わせるようにする。しかして、制御回路８の制御下で
各アンプ４ａ乃至４ｄより各コイル２ａ乃至２ｄに傾斜
磁場発生用の電流が供給され、この電流供給により所定
の傾斜磁場が形成される。ここで、各アンプ４ａ乃至４
ｄから見た負荷（コイル）のインピーダンスは、従来（
第２図）のように複数のコイルを直列接続する場合に比
して小さくなり、これにより、従来と同じ出力電圧であ
るにもかかわらず傾斜ｌａ場の立上り時間を短くするこ
とができる。In the embodiment device having the above configuration, the rise time adjustment by the slew rate limiters 7a to 7d is performed by each coil 2.
The gradient magnetic field is set to the one having the slowest rise time among a to 2d. Then, under the control of the control circuit 8, a current for generating a gradient magnetic field is supplied from each amplifier 4a to 4d to each coil 2a to 2d, and a predetermined gradient magnetic field is formed by this current supply. Here, each amplifier 4a to 4
The impedance of the load (coil) seen from d is conventionally (
This is smaller than the case where a plurality of coils are connected in series as shown in FIG. 2), and as a result, the rise time of the gradient la field can be shortened even though the output voltage is the same as the conventional one.
以上本発明の一実施例について説明したが、本発明は上
記実施例に限定されるものではなく、種々の変形実施が
可能でおるのはいうまでもない。Although one embodiment of the present invention has been described above, it goes without saying that the present invention is not limited to the above-mentioned embodiment and can be implemented in various modifications.
［発明の効果］
以上詳ｊホしたように本発明によれば、傾斜磁場の立上
り時間の高速化を図ったＭＲＩ用傾斜磁場発生装置を提
供することができる。[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide an MRI gradient magnetic field generation device in which the rise time of the gradient magnetic field is increased.
第１図は本発明一実施例の回路図、第２図は従来例の回
路図、第３図は傾斜磁場発生用電流の波形図である。
ｌａ、 ｌｂ、 ｌｃ、 １ｄ−Ｘ方向傾斜磁場コイル
、２ａ、 ２ｂ、 ２ｃ、 ２ｄ−Ｙ方向傾斜磁場コイ
ル、３ａ、 ３ｂ ・・・Ｚ方向傾斜磁場コイ
ル、４ａ、 ４ｂ、 ４ｃ、 ４ｄ−・・アンプ（電源
）。
第１図FIG. 1 is a circuit diagram of an embodiment of the present invention, FIG. 2 is a circuit diagram of a conventional example, and FIG. 3 is a waveform diagram of a current for generating a gradient magnetic field. la, lb, lc, 1d-X direction gradient magnetic field coil, 2a, 2b, 2c, 2d-Y direction gradient magnetic field coil, 3a, 3b...Z direction gradient magnetic field coil, 4a, 4b, 4c, 4d-... Amplifier (power supply). Figure 1
Claims (1)
ぞれ複数のコイルを配置して成るＭＲＩ用傾斜磁場発生
装置において、上記各コイルに対応して複数の電源を備
え、各コイル毎に単独の電源より傾斜磁場発生用の電流
を供給するようにしたことを特徴とするＭＲＩ用傾斜磁
場発生装置。In an MRI gradient magnetic field generator comprising a plurality of coils disposed for generating gradient magnetic fields in each axis direction of three orthogonal axes, a plurality of power supplies are provided corresponding to each of the coils, and a single power supply is provided for each coil. A gradient magnetic field generator for MRI, characterized in that a current for generating a gradient magnetic field is supplied.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62107560A JPS63271910A (en) | 1987-04-28 | 1987-04-28 | Gradient magnetic field generating device for mri |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62107560A JPS63271910A (en) | 1987-04-28 | 1987-04-28 | Gradient magnetic field generating device for mri |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS63271910A true JPS63271910A (en) | 1988-11-09 |
Family
ID=14462270
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62107560A Pending JPS63271910A (en) | 1987-04-28 | 1987-04-28 | Gradient magnetic field generating device for mri |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS63271910A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01227747A (en) * | 1988-03-08 | 1989-09-11 | Hitachi Ltd | Inspection device using nuclear magnetic resonance |
| JP2001309902A (en) * | 2000-04-28 | 2001-11-06 | Toshiba Corp | Magnetic resonance image instrument |
| WO2006097864A1 (en) * | 2005-03-17 | 2006-09-21 | Koninklijke Philips Electronics, N.V. | Minimum energy shim coils for magnetic resonance |
| JP2011072389A (en) * | 2009-09-29 | 2011-04-14 | Ge Medical Systems Global Technology Co Llc | Power source device and magnetic resonance imaging apparatus |
-
1987
- 1987-04-28 JP JP62107560A patent/JPS63271910A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01227747A (en) * | 1988-03-08 | 1989-09-11 | Hitachi Ltd | Inspection device using nuclear magnetic resonance |
| JP2001309902A (en) * | 2000-04-28 | 2001-11-06 | Toshiba Corp | Magnetic resonance image instrument |
| WO2006097864A1 (en) * | 2005-03-17 | 2006-09-21 | Koninklijke Philips Electronics, N.V. | Minimum energy shim coils for magnetic resonance |
| JP2011072389A (en) * | 2009-09-29 | 2011-04-14 | Ge Medical Systems Global Technology Co Llc | Power source device and magnetic resonance imaging apparatus |
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