JPS61200451A - Nuclear magnetic resonance image pick-up apparatus - Google Patents
Nuclear magnetic resonance image pick-up apparatusInfo
- Publication number
- JPS61200451A JPS61200451A JP60041642A JP4164285A JPS61200451A JP S61200451 A JPS61200451 A JP S61200451A JP 60041642 A JP60041642 A JP 60041642A JP 4164285 A JP4164285 A JP 4164285A JP S61200451 A JPS61200451 A JP S61200451A
- Authority
- JP
- Japan
- Prior art keywords
- correction
- magnetic field
- magnetic
- magnetic resonance
- static
- 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
- G01R33/3873—Compensation of inhomogeneities using ferromagnetic bodies ; Passive 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
- G01R33/28—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
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】
（イ） 産業上の利用分野
本発明は核磁気共鳴撮像装置（以下ＮＭＲ−ＣＴと称す
る）に関する。DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a nuclear magnetic resonance imaging apparatus (hereinafter referred to as NMR-CT).
（ロ） 従来の技術
最近の医療機器分野で脚光を浴びているＮＭＲ−ＣＴで
は均一度の高い静磁場を形成することが画質を向上きせ
るうえで重要である。この静磁場を形成する手段として
は常伝導磁石、超伝導磁石もしくは永久磁石が用いられ
るが、いずれも主磁石装置だけでは要求される１０ｐｐ
ｍ以下の均一性を実現することは不可能である。そこで
シムコイルと呼ばれる補正コイルを用い均一性を向上許
せている。(b) Prior Art In NMR-CT, which has recently been in the spotlight in the field of medical equipment, it is important to form a highly uniform static magnetic field in order to improve image quality. Normally conducting magnets, superconducting magnets, or permanent magnets are used as means for forming this static magnetic field, but in any case, the required 10pp is required for the main magnet device alone.
It is impossible to achieve uniformity of less than m. Therefore, a correction coil called a shim coil is used to improve uniformity.
しかしながらＮＭＲ−ＣＴ装置を実際に病院内に設置す
る場合、設置場所によっては床、天井、梁、柱等の鉄筋
（磁性体）の影響を受は静磁場の均一性が著しく悪くな
り補正コイルによる補正範囲を超えて要求される均一度
も実現できなくなる場合があり、設置場所が著しく限定
されてしまう。However, when an NMR-CT device is actually installed in a hospital, the uniformity of the static magnetic field may deteriorate significantly due to the influence of reinforcing bars (magnetic materials) such as floors, ceilings, beams, and columns depending on the installation location, and correction coils may be required. The required uniformity may not be achieved beyond the correction range, and installation locations are severely limited.
（ハ） 発明が解決しようとする問題点本発明は設置場
所が異なっても常に均一度の高い静磁場を得ることので
きるＮＭＲ−ＣＴを提供しようとするものである。(c) Problems to be Solved by the Invention The present invention aims to provide an NMR-CT that can always obtain a highly uniform static magnetic field even if the installation location is different.
（ニ） 問題点を解決する為の手段
外装体と、この外装体内に配設され補正コイルを有する
静磁場発生装置とから装置本体を構成するものにおいて
、前記装置本体に補正用磁性体を装着する機構を備える
ことにより上記問題点を解決したものである。(d) Means for solving the problem In a device whose main body consists of an exterior body and a static magnetic field generator disposed inside the exterior body and having a correction coil, a correction magnetic body is attached to the device body. The above problem is solved by providing a mechanism for doing so.
（ホ〉作用
上記手段により装置本体の設置場所に存在する周辺磁性
体の状況に応じて補正用磁性体を装置本体に装着するこ
とで、周辺磁性体による静磁場の均一性への影響を補正
コイルによる補正範囲内におさえる。(E) Effect By attaching a correction magnetic body to the device main body according to the situation of the surrounding magnetic material existing at the installation location of the device main body by the above means, the influence of the surrounding magnetic material on the uniformity of the static magnetic field is corrected. Keep it within the correction range by the coil.
（へ）実施例
本発明の一実施例を第１図〜第３図に従い説明する０図
に示すものは核磁気共鳴現象を用い非破壊的に被験体中
のスピン密度分布や緩和時間分布を求め断面像を構成出
力するための核磁気共鳴撮像装置本体で、外装体（１）
とその内部に配設きれる静磁場発生装置（２）とからな
る。(f) Example An example of the present invention will be explained according to Figs. 1 to 3. The one shown in Fig. 0 uses the nuclear magnetic resonance phenomenon to non-destructively measure the spin density distribution and relaxation time distribution in the subject. The main body of the nuclear magnetic resonance imaging device for configuring and outputting the obtained cross-sectional image, the exterior body (1)
and a static magnetic field generator (2) that can be disposed inside it.
前記外装体く１）は非磁性体製材料、例えばＦ。The exterior body 1) is made of a non-magnetic material, for example F.
Ｒ，Ｐ、や木材よりなり、天板（３）とこの天板（３）
に連結される前板（４）、後板（５）、側板（６）、（
７）とから構成きれ前板（４）と後板（５）とには被験
体く例えば人体）挿入用の楕円状第１開口（８）（９）
が形成されている。Made of R, P, and wood, the top plate (3) and this top plate (3)
Front plate (4), rear plate (5), side plate (6), (
The front plate (4) and the rear plate (5) each have an elliptical first opening (8) (9) for inserting a subject (for example, a human body).
is formed.
前記静磁場発生装置（２）は次の構成を有する。The static magnetic field generator (2) has the following configuration.
即ち、（１０）（１１）は希土類磁石材料から成る上下
一対の円板状永久磁石、（１２）（１３）は該永久磁石
の各々の一面に接して配される磁石材料から成る円板状
の上部ヨーク及び下部ヨーク、（１４）は該上部ヨーク
と電磁気的に接続きれる磁石材料から成る円筒状のサイ
ドヨークで、この上下端開口を密閉するように上部ヨー
ク（１２）及び下部ヨーク（１３）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（１０）＜１１）の対向間に強力な静磁場が形
成される。また、サイドヨーク（１４）は、上記静磁場
中への被験体の挿入用に対向配置で設けられた一対の楕
円形第２開口（１５）（１６）を有する。この第２開口
（１５）（１６）は第１開口（８）（９）に対向位置す
る。 （１７）（１８）は永久磁石（１０）（１１）の
各々の他面に対向配置で設けられ、上記静磁場の均一度
を向上きせる一対のポールピース、（１９）（２０）は
ポールピース（１７）（１８）の内側に設けた磁場補正
用の補正コイルで、定電流を流すことにより磁場の均一
性を向上させる。前記第１開口（８）（９）間には第２
開口（１５）（１６）に挿通きれる被験体挿入用の筒状
体（２１）が架設きれる。That is, (10) and (11) are a pair of upper and lower disc-shaped permanent magnets made of rare earth magnetic material, and (12) and (13) are disc-shaped discs made of magnetic material arranged in contact with one surface of each of the permanent magnets. The upper yoke and lower yoke (14) are cylindrical side yokes made of magnetic material that can be electromagnetically connected to the upper yoke, and the upper yoke (12) and the lower yoke (13) ), each of these yokes constitutes a magnetic circuit, and a strong static magnetic field is formed between a pair of opposing permanent magnets (10)<11). Further, the side yoke (14) has a pair of elliptical second openings (15) and (16) provided in opposing arrangement for insertion of a subject into the static magnetic field. The second openings (15) and (16) are located opposite to the first openings (8) and (9). (17) and (18) are a pair of pole pieces that are arranged opposite to each other on the other surfaces of the permanent magnets (10 and 11) to improve the uniformity of the static magnetic field, and (19 and 20) are pole pieces. (17) A correction coil for magnetic field correction provided inside (18) improves the uniformity of the magnetic field by flowing a constant current. A second opening is provided between the first openings (8) and (9).
A cylindrical body (21) for inserting a subject that can be inserted through the openings (15) and (16) is installed.
（２２）（２３）（２４）は外装体く１）外面に開口す
る如く外装体（１）に設けた中空状の補正用磁性体挿入
部で、必要に応じて補正用磁性体（２５）・・・が挿入
される。(22), (23), and (24) are hollow correction magnetic body insertion parts provided in the exterior body (1) so as to open on the outer surface. ... is inserted.
尚、挿入部（２２）（２３）（２４）の開口を補正用磁
性体（２５）・・・挿入後図示しない蓋体により閉室す
る。The openings of the insertion portions (22), (23), and (24) are closed by a lid (not shown) after the correction magnetic body (25) is inserted.
そして、装置本体を設置する床面（Ａ）内に存在する磁
性体（２６）からの影響が大きい場合、その影響によっ
て静磁場発生装置（２）内に形成される磁場は１７Ｚ直
交関数系で展開した時の２項、２３項の不均一が大きく
なり上記の補正コイル（１９）（２０）で補正し切れな
くなる。この２項、２３項の不均一を低減するには、静
磁場発生装置（２）に対し床面の磁性体（２６）の反対
側、即ち天板（３）の挿入部（２２）に補正用磁性体（
２５）を装着して先ず一次の大きい磁場補正を行い、次
いで補正コイル（１９）（２０）の電流調整により二次
の微少な磁場補正を行うことで、均一磁場を形成する。If the influence from the magnetic material (26) existing in the floor surface (A) on which the main body of the device is installed is large, the magnetic field formed in the static magnetic field generator (2) due to the influence is a 17Z orthogonal function system. When expanded, the non-uniformity of the 2nd and 23rd terms becomes so large that it cannot be corrected by the above-mentioned correction coils (19) and (20). In order to reduce the non-uniformity of these terms 2 and 23, it is necessary to correct the static magnetic field generator (2) on the opposite side of the magnetic body (26) on the floor, that is, on the insertion part (22) of the top plate (3). Magnetic material (
25) is attached to perform a first-order large magnetic field correction, and then a second-order minute magnetic field correction is performed by adjusting the current of the correction coils (19) and (20), thereby forming a uniform magnetic field.
前記補正用磁性体（２５）はその形状、分量を適宜選べ
るように予め複数で、かつ形状の異なるものを用意して
おくことが望ましい、又、挿入部（２２）（２３）（２
４）を挿入方向と直交する方向に複数部分に区画し、補
正用磁性体（２５）も形状の小さいものを用意して挿入
位置を選べるように構成しても良い。It is desirable to prepare a plurality of correction magnetic bodies (25) with different shapes in advance so that the shape and quantity can be selected appropriately.
4) may be divided into a plurality of parts in a direction perpendicular to the insertion direction, and the correction magnetic body (25) may also have a small shape so that the insertion position can be selected.
尚、本発明は上記実施例に限定されるもあではなく、常
伝導型或いは超伝導型の静磁場発生装置を用いた核磁気
共鳴撮像装置にも適用可能である。又、補正用磁性体（
２５）の装着位置は外装体（１）内面と篩磁場発生装置
（２）外周との間であっても良い。It should be noted that the present invention is not limited to the above-mentioned embodiments, but can also be applied to a nuclear magnetic resonance imaging apparatus using a normal-conducting or superconducting static magnetic field generator. In addition, magnetic material for correction (
25) may be installed between the inner surface of the exterior body (1) and the outer periphery of the sieve magnetic field generator (2).
（ト）効果
上記の如く構成諮れる本発明に依れば、必要に応じて補
正用磁性体を装着することで装置本体の設置場所に存在
する周辺磁性体からの影響を補正コイルで補正可能な範
囲におさえることができ、設置場所が異なっても常に要
求される静磁場の均一性を実現でき、核磁気共鳴撮像装
置本体の設置場所に対する制限をなくすることができる
。(g) Effects According to the present invention, which can be configured as described above, by attaching a correction magnetic body as necessary, it is possible to correct the influence from surrounding magnetic bodies present at the installation location of the main body of the device using a correction coil. The uniformity of the static magnetic field that is always required can be achieved even if the installation location is different, and there is no restriction on the installation location of the nuclear magnetic resonance imaging apparatus main body.
第１図〜第３＠はいずれも本発明の一実施例を示し、第
１図は概観斜視図、第２図は第１図のＩ−■線断面図、
第３図は動作説明用の要部断面図である。
（１）・・・外装体、（２）・・・静磁場発生装置、（
１９）（２０）・・・補正コイル、（２２）（２３）（
２４）・・・挿入部、（２５）・・・補正用磁性体。Figures 1 to 3 all show an embodiment of the present invention, with Figure 1 being an overview perspective view, Figure 2 being a sectional view taken along the line I-■ in Figure 1,
FIG. 3 is a sectional view of a main part for explaining the operation. (1) Exterior body, (2) Static magnetic field generator, (
19)(20)...Correction coil, (22)(23)(
24)...Insertion part, (25)...Magnetic body for correction.
Claims (1)
有する静磁場発生装置とから装置本体を構成するものに
おいて、前記装置本体に補正用磁性体を装着する機構を
備えた核磁気共鳴撮像装置。(1) A nuclear magnetic resonance device comprising an exterior body and a static magnetic field generator disposed inside the exterior body and having a correction coil, which is equipped with a mechanism for attaching a correction magnetic body to the device body. Imaging device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60041642A JPS61200451A (en) | 1985-03-01 | 1985-03-01 | Nuclear magnetic resonance image pick-up apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60041642A JPS61200451A (en) | 1985-03-01 | 1985-03-01 | Nuclear magnetic resonance image pick-up apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS61200451A true JPS61200451A (en) | 1986-09-05 |
Family
ID=12613984
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60041642A Pending JPS61200451A (en) | 1985-03-01 | 1985-03-01 | Nuclear magnetic resonance image pick-up apparatus |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61200451A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0378557A (en) * | 1989-08-18 | 1991-04-03 | Mitsubishi Heavy Ind Ltd | Ram jet combustor |
| EP0619500A1 (en) * | 1993-04-08 | 1994-10-12 | Oxford Magnet Technology Limited | Improvements in or relating to MRI magnets |
-
1985
- 1985-03-01 JP JP60041642A patent/JPS61200451A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0378557A (en) * | 1989-08-18 | 1991-04-03 | Mitsubishi Heavy Ind Ltd | Ram jet combustor |
| EP0619500A1 (en) * | 1993-04-08 | 1994-10-12 | Oxford Magnet Technology Limited | Improvements in or relating to MRI magnets |
| US5400786A (en) * | 1993-04-08 | 1995-03-28 | Oxford Magnet Technology Limited | MRI magnets |
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