New angle-independent quantitative Doppler instrument

We report on a new inexpensive instrument that provides automatic, quantitative, angle-independent Doppler measurements of velocity. This instrument requires only one transducer, a diffraction-grating-transducer, to produce multiple beams at known angles. By solving the resulting multiple Doppler equations simultaneously, both the absolute velocity and angle-to-flow are obtained. Because the beams are produced at an angle to its surface, the transducer can be placed flat on or over a vessel. Clinical experiments have shown instrument velocity accuracy of better than plus or minus 15%. Presented here are the results of clinical comparisons between measurements from conventional Duplex Doppler systems and those taken contemporaneously with the new instrument. These show the instrument's automatically-obtained velocities match those obtained from more expensive, operator-dependent conventional systems. The limits of applicability of this technique, as well as its potential for flow-quantification, cardiovascular monitoring, and implantable devices, will be presented.