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

Abstract

New designs of high-resolution ultrasonic imaging systems that operate in the 30–100MHz region, for example, those based on linear transducer systems, are currently being investigated for medical purposes. Acoustic waves with frequencies in this range can detect microscopic structures in human tissue but will typically only penetrate a few mm because of large attenuation. 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 in dermatology, which are determined by the transducer design. A linear pulsed PVDF transducer array with a center frequency around 45MHz is studied by applying numerical simulations, based on the finite element method (FEM), of this electromechanical system. Tx-beamforming properties of linear arrays with one, three, five, and seven active elements are investigated at different depths. The image quality obtained from synthetic Rx-beamforming, using responses from five electrodes, is estimated from reconstructed images of 25–100 μm thick objects. The axial and lateral resolutions of these images are found to be similar with the Tx-beamforming resolution parameters estimated from the time-derivative of the pressure beams.