Assessment of a Linear Phased Array Transducer Parameters for Brain Stimulation

Abstract

Purpose: 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.
Methods: 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.
Results: 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.
Conclusion: 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.