MAGNET SYSTEM AND MRI APPARATUS

• US 20090072939A1
• Filed: 09/12/2008
• Published: 03/19/2009
• Est. Priority Date: 09/14/2007
• Status: Abandoned Application

• Current Assignee: GE Medical Systems Global Technology Company LLC (GE Healthcare Technologies, Inc.)
• Original Assignee: GE Medical Systems Global Technology Company LLC (GE Healthcare Technologies, Inc.)
• Inventors: Zhu, Ye, Shen, Weijun, Shen, Guanghui, Hua, Yihe, Tan, Fengshun
• Application Number:
  US12/209,652
• Publication Number:
  US 20090072939A1
• Time in Patent Office: Days
• US Class Current: 335/306
• CPC Class Codes: G01R 33/3806 Open magnet assemblies for improved access to the sample, e.g. C-type or U-type magnets
• CPC Class Codes: G01R 33/383 using permanent magnets
• CPC Class Codes: H01F 7/0278 for generating uniform fields, focusing, deflecting electrically charged particles for magnetic separation by Lorentz force B03C1/023; specially adapted for NMR applications G01R33/383

Abstract

A magnet system having a pair of parallel plate-like permanent magnets in which magnetic poles of reversed polarities are opposed to each other with a space therebetween. The pair of permanent magnets includes main portions magnetized in the same direction as their thickness direction, and peripheral portions magnetized in a direction different from their thickness direction.

Claims

1. A magnet system comprising:

a pair of parallel plate-like permanent magnets in which magnetic poles of reversed polarities are opposed to each other with a space therebetween, each of said pair of permanent magnets comprising;

a main portion magnetized in a same direction as a thickness direction; and

a peripheral portion magnetized in a direction different from the thickness direction.

2. A magnet system according to claim 1, wherein each said peripheral portion comprises a border portion of the magnetic pole on a side where said pair of permanent magnets are opposed to each other.

3. A magnet system according to claim 1, wherein each said peripheral portion comprises a side circumference portion of said pair of permanent magnets.

4. A magnet system according to claim 1, wherein each said peripheral portion comprises a border portion of the magnetic poles on a side where said pair of permanent magnets are opposed to each other and a side circumference portion of each of said pair of permanent magnets.

5. A magnet system according to claim 2, wherein an angle of inclination of the magnetizing direction in each said border portion is 90 degrees to the thickness direction.

6. A magnet system according to claim 5, wherein each said border portion comprises a ring-like magnet.

7. A magnet system according to claim 3, wherein an angle of inclination of the magnetizing direction in each said side circumference portion is between 20 degrees and 50 degrees to the thickness direction.

8. A magnet system according to claim 7, wherein said angle of inclination is 25 degrees.

9. A magnet system according to claim 8, wherein each said side circumference portion comprises a ring-like magnet.

10. A magnet system according to claim 1, wherein each of said pair of permanent magnets comprises layers of soft magnetic material in magnetic poles on a first side opposite to a second side where said pair of permanent magnets are opposed to each other.

11. An MRI apparatus configured to reconstruct an image based on magnetic resonance signals collected through a magnet system having a pair of parallel plate-like permanent magnets in which magnetic poles of reversed polarities are opposed to each other with a space therebetween, gradient magnetic coils, and RF coils, said magnet system comprising:

a pair of parallel plate-like permanent magnets in which magnetic poles of reversed polarities are opposed to each other with a space therebetween, each of said pair of permanent magnets comprising;

a main portion magnetized in the a same direction as a thickness direction; and

a peripheral portion magnetized in a direction different from the thickness direction.

12. An MRI apparatus according to claim 11, wherein each said peripheral portion comprises a border portion of the magnetic poles on a side where said pair of permanent magnets are opposed to each other.

13. An MRI apparatus according to claim 11, wherein each said peripheral portion comprises a side circumference portion of said pair of permanent magnets.

14. An MRI apparatus according to claim 11, wherein each said peripheral portion comprises a border of the magnetic poles on a side where said pair of permanent magnets are opposed to each other and a side circumference portion of said pair of permanent magnets.

15. An MRI apparatus according to claim 12, wherein an angle of inclination of the magnetizing direction in each said border portion is 90 degrees to the thickness direction.

16. An MRI apparatus according to claim 15, wherein each said border portion comprises a ring-like magnet.

17. An MRI apparatus according to claim 13, wherein an angle of inclination of the magnetizing direction in each said side circumference portion is between 20 degrees and 50 degrees to the thickness direction.

18. An MRI apparatus according to claim 17, wherein said angle of inclination is 25 degrees.

19. An MRI apparatus according to claim 18, wherein each said side circumference portion comprises a ring-like magnet.

20. An MRI apparatus according to claim 11, wherein each of said pair of permanent magnets comprises layers of soft magnetic material in the magnetic poles on a first side opposite to a second side where said pair of permanent magnets are opposed to each other.