Research On Sensitivity Calibration Of Medical Hydrophone Based On Impulse Excitation Response

With the wide application of ultrasound diagnosis,physical therapy and treatment in the medical and health field,its safety and effectiveness have become the most concerned issues.It is very important to use hydrophones to measure the parameters of medical ultrasound equipment to achieve accurate characterization of the acoustic output of the transducer,and it also puts forward higher and higher requirements for the accuracy of ultrasound field parameter measurement.At present,the commonly used medical hydrophone calibration methods are based on optical interferometry and reciprocity.These methods are mainly single-frequency point calibration,and the calibration cost is relatively high.these calibration methods are mainly to measure the sensitivity of the hydrophone,but not Consider the directivity of the hydrophone and the effective size of sensitive components related to frequency.In response to these problems,the sensitivity calibration of medical hydrophones based on impulse excitation response has been studied in this paper,including sensitivity numerical calculation,directivity and effective sensitive element size measurement.The main tasks are:1.Analysis and simulation experiments compare the laser interferometry,reciprocity method and the hydrophone calibration method based on pulse excitation.The experimental results show that the combination of broadband pulse and nonlinear propagation when calibrating the hydrophone based on the pulse excitation method can achieve 1-15MHz calibration bandwidth,achieve the purpose of fast calibration,and low measurement cost.2.Based on the study of the directivity model of the hydrophone,an effective radius measurement model based on the nonlinear spatial averaging effect is given,and the correction of the sensitivity measurement of the hydrophone is realized.This method first uses the impulse excitation response to measure the voltage value of the hydrophone at different rotation angles;then,according to the effective radius measurement model of the nonlinear spatial average effect,calculates the effective radius of the hydrophone at each frequency;finally,The measured value of the sensitivity parameter of the hydrophone is corrected.The experimental results show that the effective radius measurement model modified by the nonlinear spatial average effect is feasible.3.A medical hydrophone calibration system based on impulse excitation response has been established,and the sensitivity of the hydrophone has been calibrated and corrected.On the basis of measuring the sound beam width of the hydrophone at each frequency,combined with the effective radius of the hydrophone,the correction value of the nonlinear spatial average effect is estimated,and the sensitivity calibration is realized.Finally,the sensitivity calibration uncertainty evaluation is given:the hydrophone frequency is 15MHz,the pulse excitation calibration uncertainty is up to 16.34%(k=2),the hydrophone frequency is 4MHz,and the pulse excitation calibration uncertainty The minimum is 14.08%(k=2).