The electromagnetic fields of a 64 MHz quadrature driven birdcage coil in ASTM phantom

Abstract

This study investigates the effect of the tuning conditions and losses of a radiofrequency birdcage coil on the incident field generated in a phantom. Several numerical implementations of a birdcage body coil model with variable coil losses were studied. The results showed that magnetic field at the coil isocenter (||H|| iso ), normalized to the square root of the whole body specific absorption rate, depends linearly on the coil quality factor. The latter depends non-linear on the birdcage tuning conditions and coil losses. Additionally, when realistic tuning and losses are neglected, results suggest that systematic errors of up to 35% could occur in calculated induced electric fields inside ASTM phantom.