Magnetic field generator for MRI

• US 6,340,888 B1
• Filed: 08/31/1999
• Issued: 01/22/2002
• Est. Priority Date: 09/02/1998
• Status: Expired due to Term

• Current Assignee: Sumitotmo Special Metals Co. Ltd.
• Original Assignee: Sumitomo Special Metals Co Ltd (Hitachi, Ltd.)
• Inventors: Aoki, Masaaki, Hashimoto, Shigeo
• Primary Examiner(s): ARANA, LOUIS M
• Application Number:
  US09/386,146
• Time in Patent Office: 875 Days
• Field of Search: 324/319, 324/320, 324/318, 324/322, 324/300, 335/296, 335/306, 600/422
• US Class Current: 324/319
• CPC Class Codes: G01R 33/383 using permanent magnets
• CPC Class Codes: G01R 33/3873 using ferromagnetic bodies ; Passive shimming

Abstract

A magnetic field generator for MRI comprises a pair of plate yokes opposed to each other with space in between. A magnet is provided in each of the opposed surfaces of the pair of plate yokes. A column yoke is connected to the pair of plate yokes. An enhancing member made of magnetic material and having a curved slant face is provided in an inner surface of the connection between the column yoke and the plate yokes at a place farthest from the magnet. A first bolt of magnetic field adjusting bolts is screwed into the plate yoke, with a tip of the first bolt contacting the enhancing member. A second bolt of the magnetic field adjusting bolts is screwed into the plate yoke, with a tip of the second bolt contacting an upper end face of the column yoke. An engaging portion for engagement of the enhancing member with the yoke may be provided.

Claims

1. A magnetic field generator for MRI comprising:

a pair of plate yokes opposed to each other with space in between,

a magnet provided in each of the opposed surfaces of the pair of plate yokes,

a column yoke connected to the pair of plate yokes for magnetic connection of the pair of plate yokes,

an enhancing member provided on inner surfaces in a connecting portion of the column yoke and the plate yoke, and

a fixing bolt attached to the enhancing member and to at least one of the column yoke and the plate yoke.

6. The generator according to one of claims 1 through 5, wherein the enhancing member is made of magnetic material.

7. The generator according to one of claims 1 through 5, wherein the enhancing member has a curved slant face.

2. A magnetic field generator for MRI comprising;

a pair of plate yokes opposed to each other with space in between,

a magnet provided in each of the opposed surfaces of the pair of plate yokes,

a column yoke connected to the pair of plate yokes for magnetic connection of the pair of plate yokes,

an enhancing member provided on inner surfaces in a connecting portion of the column yoke and the plate yoke, and

an engaging portion attached to at least one of the plate yoke and the column yoke, and to the enhancing member.

3. A magnetic field generator for MRI comprising:

a pair of plate yokes opposed to each other with space in between,

a magnet provided in each of the opposed surfaces of the pair of plate yokes,

a column yoke connected to the pair of plate yokes for magnetic connection of the pair of plate yokes,

an enhancing member provided at each end of a connecting portion between the column yoke and the plate yoke, in inner surfaces of the column yoke and the plate yoke, and

a first magnetic field adjusting bolt screwed into the plate yoke, with a tip of the first bolt contacting corresponding one of the enhancing members.

4. The generator according to claim 3, further comprising a second magnetic field adjusting bolt screwed into the plate yoke, with a tip of the second bolt contacting an upper end face of the column yoke.

5. A magnetic field generator for MRI comprising;

a pair of plate yokes opposed to each other with space in between,

a magnet provided in each of the opposed surfaces of the pair of plate yokes,

a column yoke having two end faces each connected to corresponding one of the plate yokes for magnetic connection of the pair of plate yokes,

a fixing bolt screwed through the plate yoke into the end face, and attached to the plate yoke and the column yoke, and

an enhancing member provided on inner surfaces in a connecting portion of the column yoke and the plate yoke.