Methods and apparatus for measuring the cross-sectional area of a duct and the volume flow rate of fluid in the duct

Abstract

The invention is particularly related to the measurement of the area of a blood vessel and the volume flow rate of blood in such vessels. An ultrasonic Doppler velocimeter which derives a number of velocity signals dependent on the number of different velocities in a duct is coupled by way of a limiter to a frequency-to-voltage converter which therefore has an output with one component for each velocity signal. A further frequency-to-voltage converter provides a signal dependent on the number of velocity signals and since this number depends on the duct area, the output from the further converter is a measure of this area. By using another frequency-to-voltage converter and a mean detector, a mean velocity signal is obtained which when multiplied by the area signal generates volume flow rate.

Dependencies are inferred from the claim text.