MAGNETIC RESONANCE IMAGING APPARATUS

• US 20080164876A1
• Filed: 12/18/2007
• Published: 07/10/2008
• Est. Priority Date: 01/05/2007
• Status: Active Grant

• Current Assignee: Toshiba Medical Systems Corporation (Canon Inc.)
• Original Assignee: Toshiba Medical Systems Corporation (Canon Inc.), Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Hanawa, Masatoshi, Sakakura, Yoshitomo
• Granted Patent: US 7,511,502 B2
• Time in Patent Office: Days
• US Class Current: 324/318
• CPC Class Codes: G01R 33/385 using gradient magnetic field coils
• CPC Class Codes: G01R 33/3856 Means for cooling the gradient coils or thermal shielding of the gradient coils
• CPC Class Codes: G01R 33/3873 using ferromagnetic bodies ; Passive shimming

Abstract

A magnetic resonance imaging apparatus includes a static magnetic field magnet which generates a static magnetic field, a gradient coil unit which generates a gradient magnetic field for overlapping with the static magnetic field, a shim unit which is disposed between the static magnetic field magnet and the gradient coil unit to control the static magnetic field, and a heat shielding member which is disposed between the gradient coil unit and the shim unit to shield a radiant heat of the gradient coil unit.

Claims

1. A magnetic resonance imaging apparatus comprising:

a static magnetic field magnet which generates a static magnetic field;

a gradient coil unit which generates a gradient magnetic field for overlapping with the static magnetic field;

a shim unit which is disposed between the static magnetic field magnet and the gradient coil unit to control the static magnetic field; and

a heat shielding member which is disposed between the gradient coil unit and the shim unit to shield a radiant heat of the gradient coil unit.

2. The magnetic resonance imaging apparatus according to claim 1, wherein the shim unit is formed so that at least one magnetic shim is disposed.

3. The magnetic resonance imaging apparatus according to claim 1, wherein the heat shielding member has a metal sheet of which a thickness is not more than a skin depth at a frequency of a gradient magnetic pulse which is supplied to the gradient coil unit.

4. The magnetic resonance imaging apparatus according to claim 3, wherein the heat shielding member is formed so that a plurality of the metal sheets are laminated with an insulation sheet interposed therebetween.

5. The magnetic resonance imaging apparatus according to claim 1, further comprising:

a cooling unit which cools the gradient coil unit.

6. The magnetic resonance imaging apparatus according to claim 5, wherein the gradient coil unit has the cooling unit disposed therein.

7. The magnetic resonance imaging apparatus according to claim 1, wherein the gradient coil unit is disposed in a vacuum state.

8. A magnetic resonance imaging apparatus comprising:

a static magnetic field magnet which generates a static magnetic field;

a gradient coil unit which generates a gradient magnetic field for overlapping with the static magnetic field;

a transmission coil which transmits a high-frequency pulse; and

a heat shielding member which is disposed between the gradient coil unit and the transmission coil to shield a radiant heat of the gradient coil unit and to shield the high-frequency pulse.

9. The magnetic resonance imaging apparatus according to claim 8, wherein the heat shielding member has a metal sheet of which a thickness is not more than a skin depth at a frequency of a gradient magnetic pulse which is supplied to the gradient coil unit and of which the thickness is not less than a skin depth at a frequency of the high-frequency pulse.

10. The magnetic resonance imaging apparatus according to claim 9, wherein the heat shielding member is formed so that a plurality of the metal sheets are laminated with an insulation sheet interposed therebetween.

11. The magnetic resonance imaging apparatus according to claim 8, further comprising:

a cooling unit which cools the gradient coil unit.

12. The magnetic resonance imaging apparatus according to claim 11, wherein the gradient coil unit has the cooling unit disposed therein.

13. The magnetic resonance imaging apparatus according to claim 8, wherein the gradient coil unit is disposed in a vacuum state.