A non-destructive temperature measurement method based on sound absorption coefficient

Abstract

This invention discloses a non-destructive temperature measurement method based on the sound absorption coefficient. It involves using an ultrasonic probe to emit ultrasonic pulses that strike a sample through a medium (pure water) at different temperatures, generating echoes. The relationship between acoustic parameters such as sound velocity and echo energy and temperature is determined by analyzing the time-shift and amplitude changes of the echoes at different temperatures. The sound absorption coefficient is inversely proportional to the cube of the sound velocity and the echo amplitude. The sound absorption coefficient is calculated using a formula, and its correlation curve with temperature is fitted. This curve is then compared with the correlation curve of measured echo energy versus temperature for verification. This method offers higher accuracy and is more suitable for non-invasive temperature measurement in tumor hyperthermia.

Description

Technical Field

[0001] This invention relates to a method for measuring the sound absorption coefficient at temperature, which utilizes the relationship between the echo changes obtained by ultrasound in media at different temperatures and temperature (echo energy decreases as temperature increases) to perform ultrasonic non-destructive temperature measurement technology. Background Technology

[0002] Currently, ultrasound is commonly used for non-destructive temperature measurement. This involves analyzing frequency-dependent sound attenuation, backscattered sound power, and the relationship between sound velocity and thermal expansion coefficient with temperature. However, the temperature sensitivity of these ultrasound methods needs improvement, and they are significantly affected by environmental factors, making them difficult to apply in practical treatments. Other methods, such as magnetic resonance imaging (MRI), impedance imaging, and microwave radiation measurement, have not yet reached practical application due to the high cost of equipment or limitations in measurement accuracy. Summary of the Invention

[0003] The present invention addresses the shortcomings of the existing technology by proposing a non-destructive temperature measurement method based on the sound absorption coefficient. This method aims to achieve more accurate and convenient non-destructive temperature measurement, making it more suitable for temperature monitoring during tumor hyperthermia and ensuring detection effectiveness.

[0004] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0005] The present invention provides a non-destructive temperature measurement method based on sound absorption coefficient, characterized by the following steps:

[0006] Step 1: Set up the experimental equipment:

[0007] Set the distance between the ultrasonic probe and the sample to d, set the sampling frequency of the TABLEUT system to f, place the sample in a beaker and place it in a constant temperature water bath, and control the initial temperature of the constant temperature water bath, beaker and sample to be the same as room temperature.

[0008] Step 2: Gradually heat the constant temperature water bath and use the TABLEUT system to collect the echo signals of the sample at different temperatures to obtain the echo images of the sample at different temperatures.

[0009] Step 3: Based on the difference between the starting point and the x-coordinate of the echo in the echo image, and combined with the sampling frequency f and distance d, the echo time shift and the speed of sound at different temperatures can be calculated.

[0010] Step 4: Calculate the theoretical sound absorption coefficient α at any temperature T according to equation (1). T Thus, the relationship curve between the sound absorption coefficient and temperature is obtained:

[0011]

[0012] In equation (1), ω is the ultrasonic frequency; ρ T c is the density of the medium in the beaker at any temperature T; T The velocity of sound is T at any temperature; η′ is the shear viscosity coefficient.

[0013] Step 5: Take the average value of the echo peak of the sample as the echo energy, compare the changes of the echo peak at different temperatures, and obtain the relationship between temperature and echo energy to achieve real-time monitoring of the sample temperature. By comparing the relationship between the theoretical sound absorption coefficient and temperature, the accuracy of the monitoring results can be verified.

[0014] The present invention provides an electronic device, comprising a memory and a processor, wherein the memory is used to store a program that supports the processor in executing the non-destructive temperature measurement method of claim 1, and the processor is configured to execute the program stored in the memory.

[0015] The present invention discloses a computer-readable storage medium on which a computer program is stored, wherein the computer program, when executed by a processor, performs the steps of the non-destructive temperature measurement method of claim 1.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] 1. This invention analyzes real-time ultrasonic echo waveforms and extracts temperature-sensitive characteristic parameters from the echoes, enabling real-time temperature measurement. This achieves effective temperature monitoring in thermotherapy and improves the accuracy and efficiency of non-destructive temperature measurement.

[0018] 2. This invention first utilizes the changes in variables that determine the sound absorption coefficient, such as sound velocity and shear viscosity coefficient, with temperature to determine the relationship between the sound absorption coefficient and temperature. Then, it verifies the measurement results by measuring the change in echo energy with temperature, thereby improving the reliability of the results.

[0019] 3. Compared with traditional thermocouple and nuclear magnetic resonance temperature measurement methods, this invention has the advantages of being non-destructive, convenient, and low-cost. Compared with the sound velocity temperature measurement method, it has higher recognition rate and accuracy. Attached Figure Description

[0020] Figure 1 The change in the x-coordinate of the marked echo start point is the change in the position of the echo sampling point at 25℃;

[0021] Figure 2 The change in the x-coordinate of the marked echo start point is the change in the position of the echo sampling point at 35℃;

[0022] Figure 3 A schematic diagram of the experimental setup for non-destructive temperature measurement using ultrasonic echo analysis;

[0023] Figure 4 The graph shows the variation of ultrasonic velocity in a medium with increasing temperature.

[0024] Figure 5 The graph shows the variation of the average echo amplitude of the medium as temperature increases.

[0025] Figure 6 The graph shows the variation of the absorption coefficient of the medium for the 2.5 MHz ultrasound emitted by the probe as the temperature increases. Detailed Implementation

[0026] In this embodiment, the experimental scenario in which a non-destructive temperature measurement method based on sound absorption coefficient is applied is as follows: Figure 3 As shown, it includes:

[0027] (1) TABLEUT System: The TABLEUT system was mainly used to acquire echo signals in the experiment. TABLEUT is a portable ultrasonic signal acquisition and display device with built-in Windows system and ultrasonic measurement software. It can drive an external ultrasonic probe to emit ultrasonic waves of a specific frequency and display the received ultrasonic signals in A-scan or B-scan mode on the system interface. It has built-in filtering and amplification functions, which can easily process the echo signals on the system interface, observe the details of the echo signals of the measured object, and support exporting the raw data in binary file format for in-depth processing. It drives the ultrasonic transmitting probe to emit ultrasonic waves with a repetition frequency of 100 Hz and a center frequency of 2.5 MHz. In the experiment, the sampling frequency was 100 MHz, and the sampling data length of a single echo was 30,000 points.

[0028] (2) Ultrasonic probe, the probe is 16cm away from the sample (ex vivo fresh pork), the obtained echo signal is saved through the TABLEUT system connected to the probe and uploaded to the computer for processing.

[0029] (3) A digital display thermometer with an accuracy of 0.1℃.

[0030] (4) It is a constant temperature water bath.

[0031] (5) is a beaker.

[0032] (6) is a sample. In this embodiment, the sample used is fresh pork from an in vitro source, which measures 13cm x 7cm x 2cm.

[0033] Specifically, this non-destructive temperature measurement method includes the following steps:

[0034] Step 1: Set up the experimental equipment:

[0035] Install the experimental equipment as follows: Figure 3As shown, the distance between the ultrasonic probe and the sample was fixed as d. The sample was placed in a beaker and then placed in a constant temperature water bath. During the experiment, the initial temperature of the constant temperature water bath, the beaker, and the excised fresh pork was controlled at the same temperature as room temperature, 25℃.

[0036] Step 2: Gradually increase the temperature using a constant-temperature water bath. Scan and store the echo signals obtained from the TABLEUT system at different temperatures. The total scanning time is 1 second, and the scanning frequency is 20 Hz. Finally, upload the stored data to a computer and use tools such as MATLAB to process the echo signals to obtain the echo positions at different temperatures.

[0037] Step 3: The ultrasonic echo signals acquired in the experiment are as follows Figure 1 and Figure 2 As shown in the figure, A represents the inherent clutter signal of the ultrasonic probe, and B represents the reflected echo from the interface between water and detached fresh pork. The vertical axis represents the relative amplitude of the ultrasonic echo, and the horizontal axis represents the number of sampling time points. Since the scanning depth is preset to 300µs and the sampling frequency to 100MHz using the TABLEUT system, the effective portion of the echo signal is approximately 30,000 points. The zero point of the echo obtained from a single scan corresponds to the starting point of the sampling synchronization control signal. By using the difference between the starting point and the horizontal axis of the echo, combined with the sampling frequency and the preset distance d between the probe and the sample, the ultrasonic velocity in the medium at a certain temperature can be calculated. Figure 1 and Figure 2 The change in the x-coordinate of the marked echo starting point represents the change in the echo sampling point position at 25℃ and 35℃. The resulting relationship between sound velocity and temperature is shown in Table 1.

[0038] Table 1

[0039]

[0040]

[0041] Step 4: Since the medium used in this invention is pure water without impurities or bubbles, and a pulse signal in the 2.5MHz ultrasonic frequency band, the effects of heat conduction and relaxation caused by the microscopic processes of the medium can be minimized. The general expression for the sound absorption coefficient can be reduced to equation (1):

[0042]

[0043] In equation (1), α T ρ is the theoretical sound absorption coefficient at any temperature T, ω is the ultrasonic frequency, and by comparing the frequency domain diagrams obtained by performing Fourier transforms on the echoes at different temperatures, the frequency of the sound wave remains almost unchanged at different temperatures; T The density of the medium (pure water) varies slightly at different temperatures, as shown in Table 1; cT η is the speed of sound at any temperature T, which can be measured by the echo position; η′ is the shear viscosity coefficient, which is generally measured by the falling ball method, multi-tube falling ball method, capillary method, rotation method, etc., and its relationship with temperature is shown in Table 1.

[0044] According to equation (1), by substituting the measured sound velocity at different temperatures, as well as the parameters such as medium density, viscosity coefficient, and ultrasonic frequency, the theoretical sound absorption coefficient at any temperature is calculated, and then the relationship curve between the sound absorption coefficient and temperature is obtained by fitting the least squares method.

[0045] Step 5: Take the average value of the echo peaks of the sample as the echo energy. To reduce error, average the abscissa and amplitude of the 20 echoes from the same scan. Use MATLAB programming for signal processing and analysis. First, preprocess the signal, including truncating the effective signal and removing overflow points. Then, fit the obtained sound velocity, echo energy, and other parameters with temperature using the least squares method. The results are as follows. Figure 4 , Figure 5 and Figure 6 As shown in the figure, the vertical axis represents sound speed, echo energy, and sound absorption coefficient, while the horizontal axis represents temperature. This allows us to obtain the relationship between temperature and echo energy, enabling real-time monitoring of the sample temperature. By comparing the theoretical sound absorption coefficient with the temperature relationship, we can verify the accuracy of the monitoring results.

[0046] In this embodiment, an electronic device includes a memory and a processor. The memory stores a program that supports the processor in executing the above-described method, and the processor is configured to execute the program stored in the memory.

[0047] In this embodiment, a computer-readable storage medium stores a computer program, which is executed by a processor to perform the steps of the above method.

Claims

1. A non-destructive temperature measurement method based on sound absorption coefficient, characterized in that, Includes the following steps: Step 1: Set up the experimental equipment: The distance between the ultrasonic probe and the sample is fixed as d. The sampling frequency of the TABLE UT system is set to f. The sample is placed in a beaker and then placed in a constant temperature water bath. The initial temperature of the constant temperature water bath, beaker, and sample is the same as that of room temperature. Step 2: Gradually increase the temperature of the constant temperature water bath and use the TABLE UT system to collect the echo signals of the sample at different temperatures, thereby obtaining the echo images of the sample at different temperatures; Step 3: Based on the difference between the starting point and the x-coordinate of the echo in the echo image, and combined with the sampling frequency f and distance d, the echo time shift and the speed of sound at different temperatures can be calculated. Step 4: Calculate the theoretical sound absorption coefficient α at any temperature T according to equation (1). T Thus, the relationship curve between the sound absorption coefficient and temperature is obtained: In equation (1), ω is the ultrasonic frequency; ρ T c is the density of the medium in the beaker at any temperature T; T The velocity of sound is T at any temperature; η′ is the shear viscosity coefficient. Step 5: Take the average value of the echo peak of the sample as the echo energy, compare the changes of the echo peak at different temperatures, and obtain the relationship between temperature and echo energy to achieve real-time monitoring of the sample temperature. By comparing the relationship between the theoretical sound absorption coefficient and temperature, the accuracy of the monitoring results can be verified.

2. An electronic device, comprising a memory and a processor, characterized in that, The memory is used to store a program that supports the processor in executing the non-destructive temperature measurement method of claim 1, and the processor is configured to execute the program stored in the memory.

3. A computer-readable storage medium storing a computer program, characterized in that, The computer program is executed by the processor to perform the steps of the non-destructive temperature measurement method of claim 1.

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