This paper was to examine the steering and focusing ability of a contact hemispherical ultrasound transducer (80 mm radius of curvature, 160 mm diameter) for transskull brain diseases therapy without skull-specific aberration correction. This work employs a simulation program to investigate the effect of ultrasound transducer parameters on the steering and focusing ability for transskull therapy. The acoustic pressure distribution and the grating lobes in tissue were used to determine the steering and focusing ability of this transducer for a set of given conditions. Simulation results demonstrated that this hemispherical phased array transducer with low frequencies can steer a high-pressure focal zone in a large range within the brain. The peak and size of the high-pressure focal zone mainly depend on ultrasound frequency and the steering distance of the focal zone. By comparing the peak pressures between the focal zone and the grating lobe, 0.1 MHz transducer performed the desired results for large ranges (140 mm x-y direction and 138 mm z direction) of beam steering. The results reveal the feasibility of using a hemispherical phased array transducer with beam steering method at low frequency for brain diseases therapy within almost full range of the brain without performing a craniectomy.
Date:
2006-12
Relation:
Biomedical Engineering - Applications, Basis and Communications. 2006 Dec;18(6):328-336.
