Transverse gradient coil

Abstract

Magnetic field gradient coils, such as those typically employed in magnetic resonance (MR) imaging employ folded loop current paths in which a first section carries current along a path close to an imaging volume. This produces a magnetic field gradient within the imaging volume. A second section, being a further radial distance from the imaging volume, carries current in a return path, in a substantially opposite current direction as the first section, thereby reducing stray magnetic fields outside of the second section. The second preferable has the same current pattern, but is slightly larger to contain magnetic fields at the fringes. A third section connects each turn of the coils in the first section to a corresponding turn of coils in the second section. This third section is disposed in a partially radial direction to connect the first and second sections. The present invention employs the return current, which is typically wasted current, to `shield` the gradient coils, reducing stray magnetic fields outside of the gradient coils, and therefore replace a second layer of `shielding` coils typically used in conventional systems. This results in a great power savings, and increased ability to rapidly change magnetic field gradients, while reducing claustrophobia, acoustic noise and a possibility of nerve stimulation.