High Frequency Ultrasound Transducers for High Definition Imaging

Abstract

Small animal imaging utilizes high frequency (15 – 120 MHz) ultrasound imaging system to obtain anatomical images of an object and visualize the progress and effects of the designed experiments. In this frequency range, single element transducers have been often used due to the limited availability of high frequency array transducers and the imaging system. The limitation of a single element based imaging system is the mechanical control of a transducer element required to obtain images. Temporal resolution, depth of field and available imaging modes are not as good as the array based imaging systems. A few forms of high frequency arrays and transducers will be presented. Array transducers use electronic beamforming, which enables higher frame rates up to 100 frames per second, larger depth of field and easier implementation of color and Doppler modes. High frequency convex arrays, phased arrays and dual element transducers are being investigated. Convex arrays give a wider field of view than linear arrays since the curved aperture can cover a trapezoidal shaped area. Phased arrays come with a smaller footprint due to a half-wavelength pitch requirement to avoid grating lobes but still offer a wide field of view by steered beams. A 20 MHz convex array, a 30 MHz phased array and 48 MHz/152 MHz dual-element intravascular transducers for preclinical and clinical imaging will be presented. High frequency arrays and transducers can provide high resolution images of any small parts adjacent to the skin or accessible through the cavity.