Method and apparatus for measuring volume fluid flow
First Claim
1. A method for use in measuring volume fluid flow, comprising:
- providing transducer means having a plurality of transducer elements;
locating said transducer means in a position for monitoring the flow of fluid through vessel means;
transmitting ultrasonic energy directed towards the vessel means using said transducer means;
receiving returned ultrasonic energy from the flowing fluid using said transducer means wherein a wide beam of returned ultrasonic energy and a narrow beam of returned ultrasonic energy are defined;
developing signals representative of said wide beam and said narrow beam;
processing said signals to provide a Doppler power spectrum associated with each of said wide beam and said narrow beam;
controlling signal amplitudes of said Doppler power spectrum associated with one of said wide beam and said narrow beam wherein said signal amplitudes are controlled at a substantially constant level;
generating a control signal using said Doppler power spectrum associated with one of said wide beam and said narrow beam; and
controlling signal amplitudes of the other of said Doppler power spectrums associated with said wide beam and said narrow beam using said control signal, wherein said signal amplitudes of said other of said Doppler power spectrums are not controlled at a substantially constant level whereby the ratio between said Doppler power spectrum associated with said wide beam and said Doppler power spectrum associated with said narrow beam is accurately maintained by reducing the level of said Doppler power spectrum associated with one of said narrow beam and said wide beam when there is an increase in said Doppler power spectrum associated with said other of said narrow beam and said wide beam.
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Accused Products
Abstract
A system is provided for measuring volume blood flow using non-invasive ultrasonic Doppler techniques. This system includes a probe assembly including a transducer having an inner transducer element and a concentric outer transducer element. A wide beam of ultrasonic energy is transmitted using the transducer and is received by a lumen area. Reflected untrasonic energy is returned to the transducer. Both the outer and inner transducer elements of the transducer are used to generate signals representative of a wide beam and a narrow beam. These generated signals include Doppler information. The signals representative of the wide beam are processed simultaneously with signals representative of the narrow beam to produce Doppler power spectrums associated with the wide and narrow beams. Phase quadrature signals are also generated for use in determining the direction of blood flow at the insonified lumen area. An AGC circuit is utilized for controlled amplitude fluctuations in the wide beam Doppler power spectrum. The control signal is also applied to the narrow beam power spectrum to avoid the introduction of inaccuracies in the subsequent computation of the ratio of wide beam power to narrow beam power. A mean frequency estimator circuit is also provided for determining the velocity of the blood flow at the insonified lumen area. The determined flow velocity is applied to a recording device for observation by the operator. The operator relies on the flow velocity trace in ensuring correct placement of the probe assembly for insonifying a desired lumen area. After it has been determined that the probe assembly is properly located, a processing/controlling unit determines volume blood flow by multiplyng the determined flow velocity by the ratio of the obtained powers in the wide and narrow beams.
38 Citations
25 Claims
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1. A method for use in measuring volume fluid flow, comprising:
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providing transducer means having a plurality of transducer elements; locating said transducer means in a position for monitoring the flow of fluid through vessel means; transmitting ultrasonic energy directed towards the vessel means using said transducer means; receiving returned ultrasonic energy from the flowing fluid using said transducer means wherein a wide beam of returned ultrasonic energy and a narrow beam of returned ultrasonic energy are defined; developing signals representative of said wide beam and said narrow beam; processing said signals to provide a Doppler power spectrum associated with each of said wide beam and said narrow beam; controlling signal amplitudes of said Doppler power spectrum associated with one of said wide beam and said narrow beam wherein said signal amplitudes are controlled at a substantially constant level; generating a control signal using said Doppler power spectrum associated with one of said wide beam and said narrow beam; and controlling signal amplitudes of the other of said Doppler power spectrums associated with said wide beam and said narrow beam using said control signal, wherein said signal amplitudes of said other of said Doppler power spectrums are not controlled at a substantially constant level whereby the ratio between said Doppler power spectrum associated with said wide beam and said Doppler power spectrum associated with said narrow beam is accurately maintained by reducing the level of said Doppler power spectrum associated with one of said narrow beam and said wide beam when there is an increase in said Doppler power spectrum associated with said other of said narrow beam and said wide beam. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for use in measuring volume fluid flow, comprising:
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providing transducer means having a first transducer element and a second transducer element; locating said transducer means in a position for monitoring the flow of fluid through vessel means; transmitting ultrasonic energy directed towards the vessel means using said transducer means; generating a first signal component using said first transducer element of said transducer means and returned ultrasonic energy; generating a second signal component using said second transducer element of said transducer means and returned ultrasonic energy, said first and second signal components being out of phase; combining said first and second signal components to provide a wide beam signal representative of a wide beam; generating a third signal component using said first transducer element of said transducer means and returned ultrasonic energy; generating a fourth signal component using said second transducer element of said transducer means and returned ultrasonic energy, said third and fourth signal components being substantially in phase; combining said third and fourth signal components to generate a narrow beam signal representative of a narrow beam, said generating of said wide beam signal and said narrow beam signal occurring at substantially the same time wherein an accurate determination of the ratio of the powers associated with said wide and narrow beams can be subsequently made; maintaining said wide beam signal and said narrow beam signal in separate circuit channels to subsequently determine the power associated with each of said wide beam and said narrow beam; determining separately a value relating to the power associated with said wide beam using said wide beam signal and a value relating to the power associated with said narrow beam signal; and after separately obtaining said power values, using each of said power values in determining the volume fluid flow. - View Dependent Claims (12, 13, 14, 15, 16)
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17. An apparatus for use in measuring volume fluid flow, comprising:
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transducer means having a first transducer element and a second transducer element, said transducer means for transmitting ultrasonic energy in a direction towards a vessel means containing moving fluid and for receiving returned ultrasonic energy from the moving fluid, said transducer means being used to define a wide beam of returned ultrasonic energy and a narrow beam of returned ultrasonic energy and for developing signals representative of said wide beam and said narrow beam; means for processing said signals to output a Doppler power spectrum associated with each of said wide beam and said narrow beam; means for determining the power in said wide beam and in said narrow beam using each of said Doppler power spectrums; means for calculating the ratio between said wide beam power and said narrow beam power; and means for controlling signal amplitudes of said narrow beam, said signal amplitudes of said one of said wide beam and said narrow beam being controlled at a substantially constant level and at least portions of said means for controlling used in controlling signal amplitudes of the other of said Doppler power spectrums of said wide beam and said narrow beam, wherein said signal amplitudes of said other of said Doppler power spectrums are not controlled at a substantially constant level whereby the ratio between said Doppler power spectrum associated with said wide beam and said Doppler power spectrum associated with said narrow beam is accurately maintained by reducing the level of said Doppler power spectrum associated with one of said narrow beam and said wide beam when there is an increase in said Doppler power spectrum associated with said other of said narrow beam and said wide beam. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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24. An apparatus for use in measuring volume fluid flow, comprising:
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transducer means including a first transducer element and a second transducer element, said transducer means for transmitting ultrasonic energy directed towards a vessel means and receiving ultrasonic energy from the vessel means; means for generating a first signal component using said first transducer element of said transducer means and returned ultrasonic energy; means for generating a second signal component using said second element of said transducer means and returned ultrasonic energy, said first and second signal components being out of phase; means for generating a third signal component using said first element of said transducer means and returned ultrasonic energy; means for generating a fourth signal component using said second element of said transducer means and returned ultrasonic energy, said third and fourth signal components being substantially in phase; means for combining said first and second signal components to generate a wide beam signal representative of a wide beam; means for combining said third and fourth signal components to generate a narrow beam signal representative of a narrow beam, said wide beam signal and said narrow beam signal being generated at substantially the same time wherein an accurate determination of the ratio of the powers associated with the wide and narrow beams can be subsequently made and wherein said wide beam signal and said narrow beam signal are generated in separate circuit channels to subsequently determine the power associated with each of said wide beam and said narrow beam; means for determining the power in said wide beam; means for determining, separately from the determination of the power in said wide beam, the power in said narrow beam; means for determining a mean frequency associate one of said wide beam and said narrow beam; means for calculating the ratio between said wide beam power and said narrow beam power; and means for determining volume fluid flow using said mean frequency and aid ratio between said wide beam power and said narrow beam power. - View Dependent Claims (25)
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Specification