EP0035325A2
Expired / Lapsed
EP
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Apparatus for measuring the cross-sectional area of a duct and the volume flow rate of fluid in the duct
Assignee: BTG International Ltd
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Filing: 1981-02-04
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Granted: —
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Expires: 2001-02-04
Abstract
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 (10, 12, 14 and 26) which derives a number of velocity signals dependent on the number of different velocities in a duct is coupled by way of a limiter 15 to a frequency-to-voltage converter 16 which therefore has an output with one component for each velocity signal. A further frequency-to-voltage converter 21 provides a signal dependent on the number of velocity signals and since this number depends on the duct area, the output from the converter 21 is a measure of this area. By using another frequency-to-voltage converter 23 and a mean detector 24, a mean velocity signal is obtained which when multiplied by the area signal generates volume flow rate.
Inventors
- 👤 Antonio Jose Sainz
- 👤 Victor Colin Roberts
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 20:43
CPC Classifications
A; A61; A61B; A61B8/00; A61B8/06; G; G01; G01F; G01F1/00; G01F1/66; G01F1/663
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
70 words
Apparatus for measuring the cross-sectional area of a duct containing a fluid, comprising means for deriving a plurality of velocity signals, each corresponding to a respective velocity of fluid in a duct, and the number of velocity signals depending on the number of different velocities concurrently present in the duct, characterised by the inclusion of analysis means for deriving an area signal representative of the number of velocity signals obtained.
Claim 2
Dependent Claim
70 words
Apparatus for measuring the cross-sectional area of a duct containing a fluid, comprising means for deriving a plurality of velocity signals, each corresponding to a respective velocity of fluid in a duct, and the number of velocity signals depending on the number of different velocities concurrently present in the duct, characterised by the inclusion of analysis means for deriving an area signal representative of the number of velocity signals obtained.
Claim 3
Dependent Claim
39 words
Apparatus according to Claim 1 wherein the analysis means comprises means for deriving a spectrum signal having one component for each velocity signal, and means for deriving a signal representative of the number of components in the spectrum signal.
Claim 4
Dependent Claim
23 words
Apparatus according to Claim 2 wherein the means for deriving the spectrum signal comprises an amplitude limiter circuit coupled to a voltage-to-frequency converter.
Claim 5
Dependent Claim
29 words
Apparatus according to Claim 2 or 3 wherein the means for deriving a signal representative of the number of components in the spectrum signal comprises a further frequency-to-voltage converter.
Claim 6
Dependent Claim
30 words
Apparatus according to Claim 4 including means coupled between the two voltage-to-frequency converters for removing low frequency signals in the output of that frequency-to-voltage converter which derives the spectrum signal.
Claim 7
Dependent Claim
20 words
Apparatus according to Claim 4 or 5 including a lineariser circuit coupled to the output of the further frequency-to-voltage converter.
Claim 8
Dependent Claim
22 words
Apparatus according to any of Claims 3 to 6 wherein at least one of the frequency-to-voltage converters comprises a phase-locked loop circuit.
Claim 9
Dependent Claim
31 words
Apparatus according to Claim 7 insofar as dependent on Claim 6 wherein the further frequency-to-voltage converter comprises a phase-locked loop and the lineariser circuit is based on a square law characteristic.
Claim 10
Dependent Claim
49 words
Apparatus according to ay preceding claim wherein the means for deriving a plurality of velocity signals comprises an oscillator coupled to an ultrasound transmission transducer, and an ultrasound transmission receiver which derives a plurality of signals each having a frequency dependent on a respective fluid velocity in the duct.
Claim 11
Independent Claim
66 words
A method of measuring the cross-sectional area of a duct containing a fluid, comprising the steps of deriving a plurality of velocity signals, each corresponding to a respective velocity of fluid in a duct and the number of signals depending on the number of different velocities concurrently present in the duct, characterised by also deriving an area signal representative of the number of velocity signals obtained.
Claim 12
Independent Claim
66 words
A method of measuring the cross-sectional area of a duct containing a fluid, comprising the steps of deriving a plurality of velocity signals, each corresponding to a respective velocity of fluid in a duct and the number of signals depending on the number of different velocities concurrently present in the duct, characterised by also deriving an area signal representative of the number of velocity signals obtained.
Claim 13
Dependent Claim
35 words
A method of measuring volume flow rate using the method of Claim 10 and additionally deriving a signal representative of mean velocity in the duct, and multiplying the signal as derived by the area signal.
References Cited (Backward Citations)
No citation records indexed.
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