Method for estimating ultrasonic attenuation coefficient using aberration compensation and reference phantom

Abstract

The present invention relates to the technical field of ultrasonic detection, and particularly, to a method for estimating an ultrasonic attenuation coefficient using aberration compensation and a reference phantom. The method comprises: separately utilizing a single transmission frequency and a plurality of different transmission frequencies to perform an ultrasonic detection on a human sample to be tested and a reference phantom; calculating center frequencies of echo signals at a depth corresponding to a starting position of a region where the ultrasonic attenuation coefficient is to be estimated; selecting a reference phantom whose center frequency is closest to that of said human sample and a transmission frequency; finally, using the selected reference phantom and transmission frequency, as well as a power spectrum of the echo signals measured from said human sample to estimate the attenuation coefficient of said human sample according to a reference phantom method. Beneficial effects are that by means of center frequency compensation at the starting depth of detection between the reference phantom and said human sample, the aberration of the signals caused by different acoustic paths of said human sample and the reference phantom can be compensated, thereby improving estimation accuracy of the ultrasonic attenuation coefficient for said human sample.

Description

A method for estimating ultrasound attenuation coefficient using aberration compensation and reference phantom Technical Field

[0001] The present invention relates to the technical field of ultrasonic detection, and in particular to a method for estimating an ultrasonic attenuation coefficient by utilizing aberration compensation and a reference phantom. Background Art

[0002] In the clinical diagnosis of fatty liver disease, the presence and extent of liver lesions are generally determined by estimating the ultrasonic attenuation coefficient of liver tissue. The current clinical method for estimating the ultrasonic attenuation coefficient is to use a reference phantom method. Specifically, the power spectra of the echo signals of the human sample to be tested and the reference phantom with a known attenuation coefficient are measured under the same transmission and reception conditions. Since the transmission and reception conditions are the same, the ratio of the power spectra of the two is only related to the difference in depth and attenuation coefficient. The attenuation coefficient of the human sample to be tested is calculated using the following formula: αsf= -d(lnSsf,zSPf,z)4dz+αPf ,in, αsf is the attenuation coefficient of the human sample to be tested, Ssf,z is the power spectrum of the echo signal of the human body sample to be tested measured at a certain transmission frequency, SPf,z is the power spectrum of the echo signal of the reference phantom measured at a certain transmission frequency. When the transmission frequency is fixed, Ssf,z and SPf,z Only related to the measurement depth z, d(lnSsf,zSPf,z)4dz The logarithm of the ratio of the power spectrum of the echo signal of the human specimen to be tested to the power spectrum of the echo signal of the reference phantom is taken as the differential value in the measurement area with respect to the measurement depth z. When estimating the ultrasonic attenuation coefficient using the reference phantom method, it is assumed that the acoustic paths of the reference phantom and the human specimen to be tested are exactly the same. This does not take into account that during ultrasonic testing of the human specimen to be tested, the ultrasonic wave will pass through transition zones with different sound velocities and attenuation coefficients, such as skin, bone, blood vessels, and fat, before reaching the actual measurement area to be measured and estimated. This difference in overall sound velocity and attenuation coefficient between the human specimen to be tested and the reference phantom leads to a certain offset and difference in their acoustic paths. Therefore, the ultrasonic attenuation coefficient estimated using the conventional reference phantom method has a large error. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for estimating the ultrasonic attenuation coefficient using aberration compensation and a reference phantom. This method can effectively compensate for the deviation caused by the different acoustic paths between the human sample to be tested and the reference phantom, thereby improving the accuracy of the ultrasonic attenuation coefficient estimation.

[0004] To achieve the above object, the present invention adopts the following technical solution: a method for estimating ultrasonic attenuation coefficient using aberration compensation and reference phantom, a human sample to be tested and N different attenuation coefficients α1, α2, α3, ... α N The ultrasonic detection is performed on the reference phantom to calculate the center frequencies of the echo signals of the human body sample to be tested and the reference phantom at the depth d, respectively. The depth d is the depth of the starting point of the measurement area of ​​the human body sample to be tested. When the ultrasonic detection is performed on the human body sample to be tested and the center frequency of the echo signal at the depth d is calculated, a single transmission frequency f0 is used to transmit and then measure and calculate the echo signal. When the ultrasonic detection is performed on N reference phantoms and the center frequency of the echo at the depth d is calculated, multiple different transmission frequencies f1, f2, f3, ... f are used for each reference phantom. m After the emission, the echo signal is measured and calculated. From the center frequencies of the echo at depth d obtained by measuring and calculating N reference phantoms at multiple different emission frequencies, a reference phantom α is selected that is closest to the center frequency of the echo signal of the human sample to be tested at depth d. i And the transmission frequency f j ; Finally, according to the formula αsf= -d(lnSsf,zSif,z)4dz+αif , calculate the attenuation coefficient of the human body sample to be tested, where, αsf is the attenuation coefficient of the human sample to be tested, d(lnSsf,zSif,z)4dz is the power spectrum of the echo signal of the human body sample to be tested at the transmission frequency f0 Ssf,z and the reference phantom at a transmission frequency of f j The power spectrum of the echo signal measured at Sif,z The logarithm of the ratio of is taken to obtain the differential value of the depth in the measurement area. αif is the attenuation coefficient of the reference phantom.

[0005] Specifically, for a human sample to be tested and N different attenuation coefficients α1, α2, α3, ... α N When ultrasonic testing is performed on a reference phantom to calculate the center frequencies of the echo signals of the human body sample to be tested and the reference phantom at a depth d, respectively, ultrasonic testing is first performed on N reference phantoms with different attenuation coefficients at different transmission frequencies, and the echo signal data of each reference phantom at different transmission frequencies is saved. During actual measurement, ultrasonic testing is performed on the human body sample to be tested and the center frequency of the echo signal at a depth d is calculated, and the center frequency of the echo signal of each reference phantom at a depth d at different transmission frequencies is calculated from the saved echo signal data.

[0006] Specifically, when calculating the center frequency of the echo signal of the human body sample to be tested and the reference body model at the depth d, the centroid method is used for calculation, and the following formula is used for calculation: fc=∫0∞fXfdf∫0∞Xfdf ,in, fc is the center frequency, f is the frequency of the echo signal, Xf is the spectrum of the echo signal at depth d.

[0007] Specifically, when calculating the attenuation coefficient of the human body sample to be tested, the power spectrum of the echo signal of the human body sample to be tested at the transmission frequency f0 is first calculated. Ssf,z and the reference phantom at a transmission frequency of f j The power spectrum of the echo signal measured at Sif,z Perform noise reduction processing and then use the formula to calculate the attenuation coefficient.

[0008] The beneficial effects of the present invention are: ultrasonic detection is performed on a human body sample to be tested and a reference phantom using a single transmission frequency and multiple different transmission frequencies respectively, and the center frequency of the echo signal at the depth at the beginning of the area where the ultrasonic attenuation coefficient is to be estimated is calculated, and a reference phantom with a center frequency closest to the human body sample to be tested and the corresponding transmission frequency are selected from them. Finally, the power spectrum of the echo signal measured with the selected reference phantom and the corresponding transmission frequency and the human body sample to be tested is used to estimate the attenuation coefficient of the human body sample to be tested according to the reference phantom method, thereby achieving compensation for the signal aberration caused by different acoustic paths of the human body sample to be tested and the reference phantom, and effectively improving the accuracy of the estimation of the ultrasonic attenuation coefficient of the human body sample to be tested. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG1 is a schematic diagram of the structures of a reference phantom and a human body sample to be tested, as well as an acoustic path during ultrasonic testing in an embodiment. DETAILED DESCRIPTION

[0010] Example 1, a method for estimating ultrasonic attenuation coefficient using aberration compensation and a reference phantom, a human body sample to be measured and N different attenuation coefficients α1, α2, α3, ... α NThe ultrasonic detection is performed on the reference phantom to calculate the center frequencies of the echo signals of the human body sample to be tested and the reference phantom at the depth d, respectively. The depth d is the depth of the starting point of the measurement area of ​​the human body sample to be tested. When the ultrasonic detection is performed on the human body sample to be tested and the center frequency of the echo signal at the depth d is calculated, a single transmission frequency f0 is used to transmit and then measure and calculate the echo signal. When the ultrasonic detection is performed on N reference phantoms and the center frequency of the echo at the depth d is calculated, multiple different transmission frequencies f1, f2, f3, ... f are used for each reference phantom. m After the emission, the echo signal is measured and calculated. From the center frequencies of the echo at depth d obtained by measuring and calculating N reference phantoms at multiple different emission frequencies, a reference phantom α is selected that is closest to the center frequency of the echo signal of the human sample to be tested at depth d. i And the transmission frequency f j ; Finally, according to the formula αsf= -d(lnSsf,zSif,z)4dz+αif , calculate the attenuation coefficient of the human body sample to be tested, where, αsf is the attenuation coefficient of the human sample to be tested, d(lnSsf,zSif,z)4dz is the power spectrum of the echo signal of the human body sample to be tested at the transmission frequency f0 Ssf,z and the reference phantom at a transmission frequency of f j The power spectrum of the echo signal measured at Sif,z The logarithm of the ratio of is the differential value of the depth in the measurement area, αif is the attenuation coefficient of the reference phantom. It should be noted that the influence of the power spectrum Ssf,z and Sif,z Contains transmission frequency f and detection depth z. When the transmission frequency is fixed, the power spectrum is only related to the detection depth. In this embodiment, by selecting a reference phantom with a center frequency closest to that of the human specimen under test at depth d and the corresponding transmission frequency, the signal aberration caused by the different acoustic paths between the human specimen under test and the reference phantom can be compensated, thereby improving the accuracy of the ultrasonic attenuation coefficient estimation.

[0011] In the estimation method of this embodiment, by using multiple different transmission frequencies to measure and calculate the center frequency of the echo signal of N reference phantoms with different attenuation coefficients, a reference phantom and transmission frequency that are closest to the center frequency of the echo signal of the human sample to be tested at a depth d can be obtained more accurately, thereby improving the efficiency of estimating the ultrasonic attenuation coefficient of the human sample to be tested.

[0012] Specifically, for a human sample to be tested and N different attenuation coefficients α1, α2, α3, ... α N When ultrasonic testing is performed on a reference phantom and the center frequencies of the echo signals of the human specimen to be tested and the reference phantom at depth d are calculated, ultrasonic testing is first performed on N reference phantoms with different attenuation coefficients at different transmission frequencies, and the echo signal data of each reference phantom at the different transmission frequencies is saved. During actual measurement, ultrasonic testing is performed on the human specimen to be tested and the center frequency of the echo signal at depth d is calculated. The center frequency of the echo signal at depth d of each reference phantom at the different transmission frequencies is then calculated from the saved echo signal data. By first performing ultrasonic testing on the N reference phantoms at multiple different transmission frequencies and saving their echo signal data, the saved echo signal data can be directly retrieved when the attenuation coefficient of the human specimen to be tested is actually measured, thereby reducing data acquisition time and improving detection and calculation efficiency.

[0013] Specifically, when calculating the center frequency of the echo signal of the human body sample to be tested and the reference body model at the depth d, the centroid method is used for calculation, and the following formula is used for calculation: fc=∫0∞fXfdf∫0∞Xfdf ,in, fc is the center frequency, f is the frequency of the echo signal, Xf is the spectrum of the echo signal at the depth d. In addition, the center frequency of the echo signal can be calculated or estimated by conventional methods in the art, in addition to the centroid method.

[0014] Specifically, in this embodiment, when calculating the attenuation coefficient of the human body sample to be tested, the power spectrum of the echo signal of the human body sample to be tested at the transmission frequency f0 is first calculated. Ssf,z and the reference phantom at a transmission frequency of f j The power spectrum of the echo signal measured at Sif,z Perform noise reduction processing and then use the formula to calculate the attenuation coefficient. By performing noise reduction processing on the power spectrum of the echo signal, the accuracy of the ultrasonic attenuation coefficient estimation of the human sample to be tested can be further improved. Specifically, the noise reduction processing of the power spectrum can be performed by filtering or other conventional noise reduction processing methods.

[0015] Of course, the above are only preferred embodiments of the present invention and are not intended to limit the scope of use of the present invention. Therefore, any equivalent changes based on the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for estimating ultrasound attenuation coefficient using aberration compensation and a reference phantom, characterized by: For the human body sample to be tested and N different attenuation coefficients α1, α2, α3, ... α N The ultrasonic detection is performed on the reference phantom to calculate the center frequencies of the echo signals of the human body sample to be tested and the reference phantom at the depth d, respectively. The depth d is the depth of the starting point of the measurement area of the human body sample to be tested. When the ultrasonic detection is performed on the human body sample to be tested and the center frequency of the echo signal at the depth d is calculated, a single transmission frequency f0 is used to transmit and then measure and calculate the echo signal. When the ultrasonic detection is performed on N reference phantoms and the center frequency of the echo at the depth d is calculated, multiple different transmission frequencies f1, f2, f3, ... f are used for each reference phantom. m After the emission, the echo signal is measured and calculated. From the center frequencies of the echo at depth d obtained by measuring and calculating N reference phantoms at multiple different emission frequencies, a reference phantom α is selected that is closest to the center frequency of the echo signal of the human sample to be tested at depth d. i And the transmission frequency f j ; Finally, according to the formula , calculate the attenuation coefficient of the human body sample to be tested, where, is the attenuation coefficient of the human sample to be tested, is the power spectrum of the echo signal of the human body sample to be tested when the transmission frequency is f0 and the reference phantom at a transmission frequency of f j The power spectrum of the echo signal measured at The logarithm of the ratio of is the differential value of the depth in the measurement area, is the attenuation coefficient of the reference phantom.

2. The method for estimating ultrasonic attenuation coefficient using aberration compensation and a reference phantom according to claim 1, characterized in that: In the human body sample to be tested and N different attenuation coefficients α1, α2, α3, ... α N When ultrasonic testing is performed on a reference phantom to calculate the center frequencies of the echo signals of the human body sample to be tested and the reference phantom at a depth d, respectively, ultrasonic testing is first performed on N reference phantoms with different attenuation coefficients at different transmission frequencies, and the echo signal data of each reference phantom at different transmission frequencies is saved. During actual measurement, ultrasonic testing is performed on the human body sample to be tested and the center frequency of the echo signal at a depth d is calculated, and the center frequency of the echo signal of each reference phantom at a depth d at different transmission frequencies is calculated from the saved echo signal data.

3. The method for estimating ultrasonic attenuation coefficient using aberration compensation and a reference phantom according to claim 1, wherein: When calculating the center frequency of the echo signal of the human body sample to be tested and the reference body model at depth d, the centroid method is used for calculation. The specific calculation is performed using the following formula: ,in, is the center frequency, is the frequency of the echo signal, is the spectrum of the echo signal at depth d.

4. The method for estimating ultrasound attenuation coefficient using aberration compensation and a reference phantom according to claim 1, wherein: When calculating the attenuation coefficient of the human body sample to be tested, first calculate the power spectrum of the echo signal of the human body sample to be tested at the transmission frequency f0. and the reference phantom at a transmission frequency of f j The power spectrum of the echo signal measured at Perform noise reduction processing and then use the formula to calculate the attenuation coefficient.

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