CALCULATING CURRENT DENSITIES AND FIELDS DUE TO SHIELDED BI-PLANAR RADIOFREQUENCY COILS

A method for the accurate computation of the current densities produce d in a wide-runged bi-planar radio-frequency coil is presented. The de vice has applications in magnetic resonance imaging. There is a set of opposing primary rungs, symmetrically placed on parallel planes and a similar arrangement of rungs on two parallel planes surrounding the p rimary serves as a shield. Current densities induced in these primary and shielding rungs are calculated to a high degree of accuracy using an integral-equation approach, combined with the inverse finite Hilber t transform. Once these densities are known, accurate electrical and m agnetic fields are then computed without difficulty. Some test results are shown. The method is so rapid that it can be incorporated into op timization software. Some preliminary fields produced from optimized c oils are presented.