Effect of phase errors on field patterns generated by an ultrasound phased-array hyperthermia applicator

The effect of phase quantization errors and Gaussian distributed random phase errors on field patterns synthesized by a rectangular ultrasound phased array hyperthermia applicator is studied. The parameters defined show that, over the range of four-bit to one-bit quantization, the simulated, patterns degrade with increasing phase errors. However, the overall shape and position of the foci remain unchanged. Simulation results show that, even with one-bit phase quantization, or with a Gaussian distributed random phase error of standard deviation of about 52 degrees , the applicator can still produce useful, if not particularly clean, power deposition patterns. Thus, the power deposition patterns are remarkably stable tolerating quite large phase error levels. This suggests that the power deposition patterns inside the body may be relatively insensitive to phase errors due to tissue inhomogeneities.