Performance of an Ultrasonic Imaging System Based on a 45-MHz Linear PVDF Transducer Array: A Numerical Study

摘要

New designs of high-resolution ultrasonic imaging systems that operate in the 30–100 MHzregion, for example, those based on linear transducer systems, are currently being investigated formedical purposes. Acoustic waves with frequencies in this range can detect microscopicstructures in human tissue but will typically only penetrate a few mm because of largeattenuation. However, this is sufficient for a diagnostic ultrasound scan of human skin. The signal-to-noise ratio and the focusing properties of the scanner are critical factors indermatology, which are determined by the transducer design. A linear pulsed PVDF transducer array with a center frequency around 45 MHz is studiedby applying numerical simulations, based on the finite element method (FEM), of thiselectromechanical system. Tx-beamforming properties of linear arrays with one, three, five,and seven active elements are investigated at different depths. The image quality obtainedfrom synthetic Rx-beamforming, using responses from five electrodes, is estimated fromreconstructed images of 25–100 μm thick objects. The axial and lateral resolutions of theseimages are found to be similar with the Tx-beamforming resolution parameters estimatedfrom the time-derivative of the pressure beams.