| 摘要 |
An RF shield is provided to prevent coupling between the gradient coils and the RF coil of an MR imaging system, wherein the RF field rotates around the RF coil axis. The shield includes a number of coaxial conductive cylinders, and further includes a plurality of cylinders formed of dielectric material, each dielectric cylinder positioned between adjacent conductive cylinders. Each conductive cylinder is formed from sheets of copper, each sheet having a pattern of conductive loops formed therein, and each loop having an associated gap to prevent induction of eddy currents therein by gradient magnetic fields produced by the MR system gradient coils. The number of conductive cylinders, and the angular orientation thereof with respect to one another, are selected to provide a plurality of closed paths for RF image current induced by the RF field, wherein respective closed paths are established by capacitive coupling between a given conductive loop of a given conductive cylinder, and conductive loops in other of the conductive cylinders.
|
