A prototype of a 500 kHz ultrasonic matricial device: beam scanner. Application to in-vivo heel bone quantitative characterization

In the context of a European Space Agency Technical Research Program, focused on bone activities in micro gravity environment, Matra Marconi Space, Vermon, LIP, ULTRASONS TECHNOLOGIES and GIP Ultrasons have been asked to develop a prototype of an ultrasonic 2D array bone densitometer. This transmission device is composed of two matrices of 24/spl times/24 elements and is functioning at 500 kHz central frequency. The test objects are scanned over a 60/spl times/60 mm/sup 2/ with an active aperture of 30 mm diameter. After the acquisition and reconstruction step, the signals are processed to extract two parametric images of attenuation and celerity. The first experiments, reported in this paper have been performed in immersion. Parametric images of in-vitro phantoms and in-vivo heel bone are presented.