Assessment of a Linear Phased Array Transducer Parameters for Brain Stimulation

Transcranial focused ultrasound (tFUS) is a safe method with high resolution to stimulate the brain tissue. By appropriate beam-forming, using a phased array transducer enables us to focus on the desired position with high resolution without moving the transducer. In this paper, the physics of tFUS propagated from a linear phased array transducer, in a 2-dimensional environment, is simulated using the k-space pseudospectral method. Furthermore, we study some factors affecting the spatial accuracy of focus point including the length of the transducer and its elements, the beam-forming and the amplitude of input pressure signal. Also, the thickness of the bone layer and the depth of focus as environmental features are considered subsequently. We investigate these parameters to propose optimum conditions in the transcranial focusing. The main contribution of this research includes: 1. computing tissue-sensitive time delays of transducer elements, 2. providing a minimum possible length of the transducer and 3. Using a neural network to determine the best possible value of the amplitude of the input pressure to get desired focus pressure that was not possible before. Based on our experiments, we obtain a significant decrease of about 32 units in the maximum error and fit a function to estimate the pressure with a correlation coefficient of approximately 0.9997.