CN105403846A - Shimming assembly of permanent magnet - Google Patents
Shimming assembly of permanent magnet Download PDFInfo
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- CN105403846A CN105403846A CN201510874356.2A CN201510874356A CN105403846A CN 105403846 A CN105403846 A CN 105403846A CN 201510874356 A CN201510874356 A CN 201510874356A CN 105403846 A CN105403846 A CN 105403846A
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- Prior art keywords
- shimming
- positive hexagonal
- hexagonal block
- permanent magnet
- plate body
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- 230000001413 cellular effect Effects 0.000 claims abstract description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 22
- 238000000034 method Methods 0.000 claims description 14
- 229910052742 iron Inorganic materials 0.000 claims description 11
- 239000000463 material Substances 0.000 claims description 8
- 229910000976 Electrical steel Inorganic materials 0.000 claims description 3
- 239000002178 crystalline material Substances 0.000 claims description 3
- 239000011810 insulating material Substances 0.000 claims description 3
- 239000002707 nanocrystalline material Substances 0.000 claims description 3
- 210000003850 cellular structure Anatomy 0.000 claims description 2
- 238000009434 installation Methods 0.000 abstract description 8
- 238000002595 magnetic resonance imaging Methods 0.000 description 5
- 239000000696 magnetic material Substances 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 230000000295 complement effect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000003745 diagnosis Methods 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 230000005415 magnetization Effects 0.000 description 1
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- Magnetic Resonance Imaging Apparatus (AREA)
Abstract
Provided in the invention is a shimming assembly of a permanent magnet. The shimming assembly is composed of a polar plate body (1), a shimming component (2), a shimming ring (3), and a gap (4) formed between the shimming ring (3) and the polar plate body (1). The shimming component (2) and the shimming ring (3) are arranged on the polar plate body (1). The shimming component (2) is formed by fixed splicing of a plurality of hexagonal blocks based on a cellular shape. The shimming assembly has advantages of simple structure, easy processing, and convenient installation and usage. The shimming requirement can be realized; the workload can be reduced; and the shimming efficiency can be improved.
Description
Technical field
The present invention relates to a kind of permanent magnet shimming assembly, belong to magnetic resonance arts.
Background technology
Carry out Accurate Diagnosis in order to obtain clear real image fast to patient, magnetic resonance imaging system requires that magnet wherein can provide a very uniform space magnetic field on a large scale.The main magnet of permanent-magnet type MRI is after assembling, and the unevenness in magnetic field, sample area is often at 1000 ~ 1500ppm, or higher.Therefore, in the urgent need to being improved the uniformity coefficient of main magnet by shimming means.For the magnet having pole plate for reaching this object it is crucial that the design of body even field assembly.Method for shimming mainly contained two kinds in the past: initiatively shimming and passive shimming.Initiatively shimming is exactly arrange one group of current coil at the suitable position of magnet, and when energized, harmonic component uneven in basic field can be offset in the magnetic field that coil produces.
The method is through being usually used in often leading and superconducting magnet.For Open-style Permanent Magnet MRI magnet, consider that its basic field uniformity leads difference than often, and open in order to not destroy it, the passive method for shimming of main employing.Passive method for shimming is exactly at permanent magnet pole surface mount small iron plate or little magnetic sheet, and the complementary field produced by iron plate or magnetic sheet eliminates the non-homogeneous component in main field, thus the magnetic field of sample area is reached be uniformly distributed.Current conventional passive method for shimming shortcoming is just, the sheet number of magnetic sheet is chosen and orientation problem still mainly relies on the experience of technician, and manual test workload is large, shimming efficiency is low.
Summary of the invention
The object of the invention is to overcome the deficiencies in the prior art part, a kind of magnetic resonance imaging shimming assembly is provided.This shimming assembly is drawn materials easily, and low price is easy for installation, under the prerequisite not affecting MRI magnet opening size, can significantly improve MRI magnetic field's regularity.
Permanent magnet shimming assembly of the present invention, by pole plate body (1), be located at shimming parts (2) on pole plate body (1) and grading ring (3), the air gap (4) be located between grading ring (3) and pole plate body (1) formed, described shimming parts (2) by multiple positive hexagonal block by cellular fixing assembled.
Described pole plate body (1) is circular, is made up of pure iron; Pole plate body should be made during magnet design to be in undersaturated condition.
The positive hexagonal block of described shimming parts (2) is made up of pure iron material, silicon steel material, non-crystalline material or nanocrystalline material; The core of said shimming parts is not limited to the one in foregoing four kinds of materials, as long as the good soft magnetic material of residual magnetic flux density higher coercivity lower magnetization curve squareness can.
Said grading ring (3) is processed into by pure iron;
Air gap (4) between described grading ring (3) and pole plate body (1) is made up of the insulating material of high resistance height magnetic resistance.
The surface of the gap in described shimming parts between positive hexagonal block and positive hexagonal block adopts chemistry or heat-treating methods to improve overall resistance reduction magnetic resistance, and improves positive hexagonal block insulating property each other.
The shape of described shimming parts is stepped cellular structure; The erection method of shimming parts is: the 1st piece, center positive hexagonal block-the 1st periphery positive hexagonal block (2,3,4,5,6, No. 7 positive hexagonal blocks) ... the positive hexagonal block of-N periphery (quantity is 6N).The surface of contact of adjacent positive hexagonal block will be parallel to each other, mutually insulated between adjacent positive hexagonal block.
The diameter of described single positive hexagonal block is 10 ~ 30mm, and the gap between adjacent positive hexagonal block is 0.1 ~ 0.2mm.
The height of described single positive hexagonal block is 10 ~ 30mm.
Can produce in work space certain area uniform magnetic field distribution, to be divided by two groups of magnetic materials relatively put structure the formation, two one facing to said work space, the shimming assembly of the permanent magnet that the connection yoke of dredging yoke that another side and said magnetic material divide the pole plate assembly be connected of structuring the formation, two one end and one group of said magnetic material divide the other end of structuring the formation to be connected space towards the outside forms is made up of pole plate body, shimming parts, grading ring and the air gap between grading ring and pole plate.
The distribution curve of the present invention's foundation magnetic field homogeneity carries out the design and installation of shimming assembly, the uniformity value of the initial fields of permanent magnet was at 1000 ~ 1500PPM in the past, the uniformity value of initial magnetic field can be reduced to 400 ~ 800PPM by the installation of this shimming assembly, for follow-up accurate shimming saves the plenty of time.
Advantage of the present invention is that structure is simple, handling ease, easy to install.Maximum feature is the requirement that both can reach shimming, can save workload again, improves shimming efficiency.
Accompanying drawing explanation
Shown in Fig. 1 is the schematic diagram of pole plate body, shimming parts, grading ring and the air gap between grading ring and pole plate.
Fig. 2 is that the one of positive hexagonal block fixes erection method, keeps between adjacent positive hexagonal block
Certain gap, is become stepwise to be layered on pole plate to surrounding by center.Wherein the 1st piece of positive hexagonal block is fixed on the center of pole plate, then 2,3,4,5,6, No. 7 positive hexagonal blocks around the 1st are fixedly mounted successively according to the sequence number marked in figure, 8,9,10,11,12,13,14,15,16,17,18, No. 19 around 2nd positive hexagonal blocks, 20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36, No. 37 around the 3rd positive hexagonal blocks.The erection sequence that the installation remaining positive hexagonal block is not fixed, only need fill up the plate regions of regulation, the mode that its fixed form adopts screw to connect.
Fig. 3 is the schematic diagram of adjacent positive hexagonal block, and the diameter of shown positive hexagonal block is 10 ~ 30mm, and the gap between adjacent positive hexagonal block is at 0.1 ~ 0.2mm.
Fig. 4 is the schematic perspective view of positive hexagonal block, and the height of shown positive hexagonal block is at 10 ~ 30mm.
Fig. 5 is that the another kind of positive hexagonal block fixes erection method, the black ring around positive hexagonal block
Shape region is reserved area, and be used for finally finely tuning the position of positive hexagonal block, the peripheral diameter of annular region is 900mm.
Wherein, 1 is pole plate body, and 2 is shimming parts, and 3 is grading ring, and 4 is air gap.
Embodiment
As shown in Figure 1, permanent magnet shimming assembly of the present invention, by pole plate body (1), be located at shimming parts (2) on pole plate body (1) and grading ring (3), the air gap (4) be located between grading ring (3) and pole plate body (1) formed, described shimming parts (2) by multiple positive hexagonal block by cellular fixing assembled.
Described pole plate body (1) is circular, is made up of pure iron; Pole plate body should be made during magnet design to be in undersaturated condition.
The positive hexagonal block of described shimming parts (2) is made up of pure iron material, silicon steel material, non-crystalline material or nanocrystalline material;
Said grading ring (3) is processed into by pure iron;
Air gap (4) between described grading ring (3) and pole plate body (1) is made up of the insulating material of high resistance height magnetic resistance.
The surface of the gap in described shimming parts between positive hexagonal block and positive hexagonal block adopts chemistry or heat-treating methods to improve overall resistance reduction magnetic resistance, and improves positive hexagonal block insulating property each other.
As shown in Figure 2, be that the one of positive hexagonal block fixes erection method, between adjacent positive hexagonal block, keep certain gap, become stepwise to be layered on pole plate to surrounding by center.Wherein the 1st piece of positive hexagonal block is fixed on the center of pole plate, then 2,3,4,5,6, No. 7 positive hexagonal blocks around the 1st are fixedly mounted successively according to the sequence number marked in figure, 8,9,10,11,12,13,14,15,16,17,18, No. 19 around 2nd positive hexagonal blocks, 20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36, No. 37 around the 3rd positive hexagonal blocks.The erection sequence that the installation remaining positive hexagonal block is not fixed, only need fill up the plate regions of regulation, the mode that its fixed form adopts screw to connect.The surface of contact of adjacent positive hexagonal block will be parallel to each other, mutually insulated between adjacent positive hexagonal block.
As shown in Figure 5, be that the one of positive hexagonal block fixes erection method, the Black circles region around positive hexagonal block is reserved area, and be used for finally finely tuning the position of positive hexagonal block, the peripheral diameter of annular region is 900mm.
As shown in Figure 3, the diameter of single positive hexagonal block is 10 ~ 30mm, and the gap between adjacent positive hexagonal block is at 0.1 ~ 0.2mm.
As shown in Figure 4, the height of single positive hexagonal block is at 10 ~ 30mm.
The distribution curve of the present invention's foundation magnetic field homogeneity carries out the design and installation of shimming assembly, the uniformity value of the initial fields of permanent magnet was at 1000 ~ 1500PPM in the past, the uniformity value of initial magnetic field can be reduced to 400 ~ 800PPM by the installation of this shimming assembly, for follow-up accurate shimming saves the plenty of time.
Claims (6)
1. a permanent magnet shimming assembly, it is characterized in that, by pole plate body (1), be located at shimming parts (2) on pole plate body (1) and grading ring (3), the air gap (4) be located between grading ring (3) and pole plate body (1) formed, described shimming parts (2) by multiple positive hexagonal block by cellular fixing assembled.
2. permanent magnet shimming assembly according to claim 1, is characterized in that,
Described pole plate body (1) is circular, is made up of pure iron;
The positive hexagonal block of described shimming parts (2) is made up of pure iron material, silicon steel material, non-crystalline material or nanocrystalline material;
Said grading ring (3) is processed into by pure iron;
Air gap (4) between described grading ring (3) and pole plate body (1) is made up of the insulating material of high resistance height magnetic resistance.
3. permanent magnet shimming assembly according to claim 1, it is characterized in that, the surface of the gap in described shimming parts between positive hexagonal block and positive hexagonal block adopts chemistry or heat-treating methods to improve overall resistance reduction magnetic resistance, and improves positive hexagonal block insulating property each other.
4. permanent magnet shimming assembly according to claim 1, is characterized in that, the shape of described shimming parts is stepped cellular structure; The erection method of shimming parts is: the 1st piece, the center positive hexagonal block of positive hexagonal block-the 1st periphery, i.e. 2,3,4,5,6, No. 7 positive hexagonal blocks, until the positive hexagonal block of N periphery, quantity is 6N.
5. permanent magnet shimming assembly according to claim 1, is characterized in that, the diameter of described single positive hexagonal block is 10 ~ 30mm, and the gap between adjacent positive hexagonal block is 0.1 ~ 0.2mm.
6. permanent magnet shimming assembly according to claim 1, is characterized in that, the height of described single positive hexagonal block is 10 ~ 30mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510874356.2A CN105403846A (en) | 2015-12-02 | 2015-12-02 | Shimming assembly of permanent magnet |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510874356.2A CN105403846A (en) | 2015-12-02 | 2015-12-02 | Shimming assembly of permanent magnet |
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| CN105403846A true CN105403846A (en) | 2016-03-16 |
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| CN201510874356.2A Pending CN105403846A (en) | 2015-12-02 | 2015-12-02 | Shimming assembly of permanent magnet |
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2275251Y (en) * | 1996-12-17 | 1998-02-25 | 中国科学院武汉物理与数学研究所 | Permanent magnet for nuclear magnetic resonance analyzer |
| CN2404130Y (en) * | 1999-12-01 | 2000-11-01 | 深圳市万济高科技产业投资发展有限公司 | Magnet apparatus using for magnetic resonance imaging system |
| CN1401295A (en) * | 2001-08-29 | 2003-03-12 | 中国科学院武汉物理与数学研究所 | Permanent magnet for nuclear magnetic resonance image-forming apparatus |
| CN202870284U (en) * | 2012-07-26 | 2013-04-10 | 宁波鑫高益磁材有限公司 | Active shimming system used for magnetic resonance imaging permanent magnet |
| CN104407314A (en) * | 2014-11-26 | 2015-03-11 | 江苏美时医疗技术有限公司 | Permanent magnet anti-eddy unit |
| CN205507055U (en) * | 2015-12-02 | 2016-08-24 | 江苏美时医疗技术有限公司 | Permanent magnet shimming subassembly |
-
2015
- 2015-12-02 CN CN201510874356.2A patent/CN105403846A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2275251Y (en) * | 1996-12-17 | 1998-02-25 | 中国科学院武汉物理与数学研究所 | Permanent magnet for nuclear magnetic resonance analyzer |
| CN2404130Y (en) * | 1999-12-01 | 2000-11-01 | 深圳市万济高科技产业投资发展有限公司 | Magnet apparatus using for magnetic resonance imaging system |
| CN1401295A (en) * | 2001-08-29 | 2003-03-12 | 中国科学院武汉物理与数学研究所 | Permanent magnet for nuclear magnetic resonance image-forming apparatus |
| CN202870284U (en) * | 2012-07-26 | 2013-04-10 | 宁波鑫高益磁材有限公司 | Active shimming system used for magnetic resonance imaging permanent magnet |
| CN104407314A (en) * | 2014-11-26 | 2015-03-11 | 江苏美时医疗技术有限公司 | Permanent magnet anti-eddy unit |
| CN205507055U (en) * | 2015-12-02 | 2016-08-24 | 江苏美时医疗技术有限公司 | Permanent magnet shimming subassembly |
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Application publication date: 20160316 |