Local transverse gradient coil

• US 5,293,126 A
• Filed: 11/09/1992
• Issued: 03/08/1994
• Est. Priority Date: 11/09/1992
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Schaefer, Daniel J.
• Primary Examiner(s): Tokar, Michael J.
• Application Number:
  US07/973,444
• Time in Patent Office: 484 Days
• Field of Search: 324/300, 324/307, 324/309, 324/318, 324/322, 128/653.5
• US Class Current: 324/318
• CPC Class Codes: G01R 33/34046 Volume type coils, e.g. bird-cage coils; Quadrature bird-cage coils; Circularly polarised coils
• CPC Class Codes: G01R 33/385 using gradient magnetic field coils
• CPC Class Codes: G01R 33/3854 means for active and/or passive vibration damping or acoustical noise suppression in gradient magnet coil systems

Abstract

A local coil assembly includes an RF coil disposed inside a cylindrical form and a pair of z-axis gradient coils wound around the outside of the cylindrical form. First and second pairs of gradient coils are mounted on opposite sides and extend radially outward from the cylindrical form. These pairs of gradient coils produce a gradient field perpendicular to the z-axis with minimal effect on the operation of the RF coil.

Claims

1. A coil assembly for use in an NMR system that produces a polarizing magnetic field, which comprises:

a cylindrical form disposed around a central opening and having a central axis aligned with the polarizing magnetic field of the NMR system;

a first pair of gradient coils mounted to one side of the cylindrical form for producing a first magnetic field which is oriented substantially parallel to the polarizing magnetic field within the central opening and is directed in a first direction therealong; and

a second pair of gradient coils mounted to a side opposite to said one side of the cylindrical form for producing a second magnetic field which is oriented substantially parallel to the polarizing magnetic field within the central opening and is directed in a second direction therealong which is opposite to the direction of the first magnetic field;

each gradient coil having a set of loops oriented in planes which are tilted from a plane perpendicular to the central axis and the first and second magnetic fields having a gradient perpendicular to the polarizing magnetic field.

2. The coil assembly as recited in claim 1 in which an RF coil is disposed inside said cylindrical form.

3. The coil assembly as recited in claim 1 which includes a third pair of gradient coils wound around the cylindrical form to produce a third magnetic field oriented in the direction of the polarizing magnetic field and said third magnetic field having a gradient in the direction of the polarizing magnetic field.

4. The coil assembly as recited in claim 1 in which the cylindrical form has a viewing port therein for access to a subject disposed in the central opening defined by the cylindrical form.

5. The coil assembly as recited in claim 1 in which opposing gradient coils in the first and second pairs of gradient coils are mounted to the cylindrical form by brackets which fasten to and cradle the cylindrical form.

6. The coil assembly as recited in claim 1 in which the second pair of gradient coils is a mirror image of the first pair of gradient coils.