Cylindrical Diffraction-Grating Transducers for Accurate Blood Flow Measurement
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Solution Overview
Problem
Conventional Doppler ultrasound methods for measuring blood flow in vessels are inaccurate due to sampling only a small portion of the flow and extrapolating results, which can lead to incorrect measurements, especially when flow is not parallel to the vessel axis.
Innovation Solution
A configuration using cylindrical diffraction-grating and non-diffraction-grating transducers that produce Doppler signals only from axial flow components, ensuring accurate measurement of flow through most of the vessel's cross-section by creating equiphase planes perpendicular to the vessel axis, thus filtering out non-axial components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional Doppler ultrasound methods sample only a small portion of the flow through a vessel and extrapolate flow from that sample, then the measurement process is simplified, but the measurement accuracy deteriorates
Solution Approach 1:
The vessel wall is segmented into multiple transducer elements arranged circumferentially, allowing the flow measurement to be divided into multiple sampling zones across the vessel cross-section. Each transducer element samples flow in its specific angular sector, and the results are integrated to provide comprehensive flow measurement across the entire vessel, eliminating the need for extrapolation from a single small sample.
2Loss of information
If conventional Doppler methods measure all flow components including non-axial components, then more comprehensive flow information is obtained, but measurement accuracy for volume flow deteriorates due to inclusion of non-contributing components
Solution Approach 1:
Each transducer element is positioned and oriented to have its beam axis tangent to the vessel wall, creating localized measurement zones that preferentially sample axial flow components. The angular arrangement of multiple elements ensures that each element's measurement zone is optimized for detecting flow parallel to the vessel axis while naturally filtering out non-axial components through geometric selection, rather than measuring all components and processing them mathematically.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration provides more accurate measurements of blood flow by isolating axial velocity components, ensuring that only the flow direction contributes to the measurement, improving the accuracy of flow volume calculations.
Implementation Method 1
When they are insonated by a beam of ultrasound their movement creates a Doppler shift in the scattered sound. The amount of shift in frequency, also known as the Doppler shift, is proportional to the number of wavelengths of ultrasound per second that the red blood cell moves.
Implementation Method 2
cylindrical DGT (or diffraction-grating transducer)
Implementation Method 3
The wavefronts launched by the cylindrical DGT 102 on opposite walls of the vessel produces planes of 'standing waves', i.e. equiphase plane as expressed by lines 104, perpendicular to the vessel axis.
Data Source
AI summary
The velocity of fluids containing particles that scatter ultrasound can be measured by determining the Doppler shift of the ultrasound scattered by the particles in the fluid. Measuring fluid flow in cylindrical vessels such as blood vessels is an important use of Doppler ultrasound. This invention teaches using various configurations of cylindrical diffraction-grating transducers and cylindrical non-diffraction-grating transducers that suppress the Doppler shift from non-axial components of fluid velocity while being sensitive to the Doppler shift produced by axial velocity components. These configurations thus provide accurate measurement of the net flow down the vessel, even when the fluid flow is curved or not parallel to the vessel wall.