V.K. Klochko1, I.V. Andreeva2

1 Ryazan State University of Radio Engineering named after V.F. Utkin (Ryazan, Russia)

2 Ryazan State Medical University named after Academician I.P. Pavlov (Ryazan, Russia)

In modern medical methods of non-invasive diagnostics of vessels condition, attention is paid to ultrasound sensors using Doppler methods for measuring blood flow rate. Instruments for measuring the speed of blood flow in vessels using ultrasonic sensors are usually single-channel and use one receiving-transmitting sensor that emits and receives a reflected ultrasonic signal. At the same time, there are approaches based on multi-channel processing of signals with sequential radiation and reception of signals in the direction of the selected vessel test control volume by several sensors. Such approaches use spatial model of velocity vector measurements by its three projections. There are also approaches based on the use of single-channel sensors and their sequential radiation in the direction of two test control volumes of the vessel, based on a flat model for determining the velocity vector from two of its projections.

All these approaches have certain disadvantages in their practical application. Thus, uni-channel devices widely used in medical diagnostics give an opportunity of real-time measurements of blood flow rate, however, the measurement result is significantly influenced by the angle between the propagation of the ultrasonic beam and the direction of blood flow in the vessel. Multi-channel sensors are designed to eliminate this drawback, since when the specified angle changes, the projections of the speed vector change, and the speed vector itself remains unchanged.

However, the implementation of the idea of multi-channel suffers from a number of disadvantages. First, sequential radiation by several sensors violates the principle of synchronism of the emitters, as a result, different time phases of the blood flow rate are measured, which leads to errors in measuring the speed. Secondly, the proposed method of attachment of sensors requires preliminary adjustment of several angles of radiation directions, angles of mutual orientation of movable elements of sensors and is limited by measurement of blood flow rate in vessels of arm or leg. Thirdly, the question of improving the accuracy of measuring the distances from the sensor to the selected control volumes of vessel and direction angles of the sounding rays remains open.

The purpose of the work − to increase the efficiency of functioning the ultrasound diagnostics devices by obtaining stable estimates of the blood flow rate in the vessels of any part of the body and the convenience of real-time measurements of medical personnel.

To achieve the goal, a method and algorithm for multi-channel measurement of blood flow speed are proposed, characterized by an algebraic approach to estimating the speed vector from the position of the proposed criterion and allowing to find estimates of the speed vector in the coordinate system of the device on any part of the body regardless of the inclination of the device with a simpler adjustment of the device by one corner in real time. The approach is based on multi-channel processing of ultrasonic signals received by a system of sensors oriented in a single coordinate system with one common angle of rotation relative to the direction of ultrasonic beam. The approach differs by the presence of a criterion that allows you to synthesize the algorithm for estimating the velocity vector from the position of this criterion, as well as analyze the accuracy of obtained estimates. Based on the proposed approach, a method for measuring the speed of blood flow and an algorithm for its implementation was developed. The statistical error of the speed estimates is calculated, showing the permissible percentage of error. Method and algorithm can be implemented on a modern element base.

Klochko V.K., Andreeva I.V. Measurement of blood flow rate by ultrasonic sensor system. Biomedicine Radioengineering. 2023. V. 26. № 1. Р. 73-81. DOI: https://doi.org/10.18127/j15604136-202301-08 (In Russian).

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