ASA 125th Meeting Ottawa 1993 May

3pPA5. Feasibility of a mechanical waveguide to control the ultrasonic field in pulsed Doppler blood flow measurement.

James J. Finneran

Mardi C. Hastings

Dept. of Mech. Eng., Ohio State Univ., 206 W. 18th Ave., Columbus, OH 43210

The location and size of the sample volume is of considerable importance in pulsed Doppler blood flow detection and velocity measurement. This study examines the feasibility of using a mechanical waveguide to control the ultrasonic field (and thus the sample volume size) of a flat disk transducer operated in pulse-echo mode. The waveguide controls the axial location of the natural focus and the lateral beam width at the natural focus. Experimental measurements are compared to theoretical results derived from a transient field model of the pulse-echo system. Results confirm that the waveguides offer a potentially useful and inexpensive means of altering the pulse-echo field of a flat disk transducer. [Work supported by NSF Grant No. MSS 9058607.]