Simulation Study Of Multiple Focal Points Based On The Concave Transducer With Multiple Elements

Medical ultrasound with non-invasive,low-cost and real-time characteristics is widely applied in many clinical fields involved with almost all the body's organs and medical branches.Based on the fundamental physical characteristics and the biological effects of cavitation and thermal effects,medical ultrasound can realize imaging diagnosis,neural modulation,thermal ablation and other functions.Ultrasound neuron modulation and thermal ablation applications belong to therapeutic ultrasound,based primarily on ultrasound mechanical effects and thermal effects.Ultrasound nerve control and thermal ablation make use of the focusing of ultrasonic transducer through controlling the stimulation signals.In this paper,we first study the multi-point focusing algorithm of concave ultrasonic transducer with multi-elements.It includes pseudo-inverse algorithm,random superposition algorithm and weighted Gerchberg-Saxton algorithm.We implement and compare the three algorithms based on the homogeneity and efficiency.Because of the feasibility of multi-focus simulation experiment,two concrete applications are put forward.Firstly,"ultrasonic retina" was proposed as well which applied ultrasound to stimulate the retina which induced an action potential similar with light elimination.But the implementation of ultrasonic retina device is not developed well.This paper proposes a novel method of contact-lens for implementation of such a device.The transducer was fabricated as a contract-lens shape which provides an easy method to achieve the acoustic coupling with eye liquid.The key parameters of ultrasound transducer were simulated and results were presented for achieving ultrasonic focus,multiple-site focus,and 2D pattern generation.Secondly,based on the parameters of the physical transducer,this study realizes the application of high intensity focused ultrasound focusing with multiple focal points.Multi-point simultaneously work increase the focal area aimed at target tissue.It can effectively solve the problem of low efficiency caused by single-point scanning and the problem of residual cancer cells in the target area due to the small single stimulation area.This not only shortens the treatment time,but also reduces the possibility of tumor recurrence caused by residual cancer cells.It demonstrated that the proposed contact-lens based ultrasound phased array is suitable for multiple-focus neuro-stimulation,which is potentially for ultrasonic retina prosthesis.Also,the simulation results can instruct high intensity focus ultrasound to be applied in stimulation with multiple focal points.