Numerical simulation of annular phased arrays for anatomically based models using the FDTD method

Annular phase arrays (APAs) of aperture and dipole antennas used for hyperthermia are simulated in three dimensions by using the finite-difference time-domain (FDTD) method. A 17363 cell, 1.31 cm resolution, anatomically based model of the human torso surrounded by a bolus of deionized water is used for calculations of specific absorption rates (SARs). Test runs on the calculation of fields in the water-filled interaction space and with homogeneous circular- and elliptical-cylinder phantoms correlate well with the experimental data in the literature, lending support to the accuracy of the FDTD method for near-field exposure conditions. Results are given for APAs using different sizes of aperture and dipole antennas and for a subannular array to obtain higher SARs in the liver. It is concluded that, because of its flexibility, the proposed procedure may be useful for a variety of realistic radiofrequency applicators for hyperthermia and other biomedical applications