Method and device for detecting elasticity of viscous elastic medium

1. A method for detecting an elasticity of a viscoelastic medium, comprising steps of:

a) detecting with a pressure sensor array a pressure applied to the viscoelastic medium by an ultrasonic transducer probe;

b) detecting with the pressure sensor array a verticality of the ultrasonic transducer probe relative to the viscoelastic medium;

c) in response to the detected pressure and the detected verticality satisfying preset conditions, driving the ultrasonic transducer probe with a vibration by a vibrator so as to produce an elastic wave to be propagated in the viscoelastic medium, transmitting an ultrasonic wave to the viscoelastic medium by the ultrasonic transducer probe at a pulse repetition frequency of 100 Hz-100000 Hz, and collecting through the ultrasonic transducer probe an ultrasonic echo returned from the viscoelastic medium and corresponding to the transmitted ultrasonic wave;

d) selecting an effective ultrasonic echo from the ultrasonic echo according to a duration of the vibration and physical parameters of the viscoelastic medium, wherein the ultrasonic transducer probe stops vibrating and the elastic wave is propagated in the viscoelastic medium at a moment corresponding to the effective ultrasonic echo;

e) calculating a propagation velocity of the elastic wave in the viscoelastic medium according to the effective ultrasonic echo; and

f) calculating the elasticity of the viscoelastic medium according to the propagation velocity of the elastic wave.

2. The method according to claim 1 , wherein the step b) comprises:

a serial number N select of an effective ultrasonic signal scanning line satisfying:

N select ≧ceiling(( T+ΔT )× F high ),

where ceiling(.) is a ceiling rounding function, F high is a pulse repetition frequency of transmitting an ultrasonic signal and is within a range from 100 Hz to 100000 Hz, T is the duration of the vibration, the ultrasonic transducer probe completely stops vibrating after the vibration starts for a period of T+ΔT, and the ultrasonic signal scanning line is a collected ultrasonic echo corresponding to an transmitted ultrasonic pulse;

when the elastic wave is still propagated in the viscoelastic medium, the serial number N select of the effective ultrasonic echo scanning line satisfying:

N select ≦ceiling(( D 1 /V s1 +T )× F high ),

where D 1 is a thickness of the viscoelastic medium, V s1 is a lower limit of the propagation velocity of the elastic wave in the viscoelastic medium determined according to an estimated hardness range and an estimated density of the viscoelastic medium;

when ΔT is less than D 1 /V s1 , by combining above two formulae, N select satisfying:

ceiling(( T+ΔT )× F high )≦ N select ≦ceiling(( D 1 /V s1 +T )× F high ); and

when ΔT is not less than D 1 /V s1 , an elastic intermediate medium with a thickness of D 2 and a first hardness is added between the ultrasonic transducer probe and the viscoelastic medium so that ΔT<D 1 /V s1 +D 2 /V s2 , where V s2 is a propagation velocity of the elastic wave in the elastic intermediate medium, then the serial number N select of the effective ultrasonic signal scanning line satisfying:

ceiling(( T+ΔT )× F high )≦ N select ≦ceiling(( D 2 /V s2 +D 1 /V s1 +T )× F high ).

3. The method according to claim 1 , wherein a vibration frequency f of the vibration is between 0.5 Hz and 3000 Hz, and the duration of the vibration is between ½f and 40/f.

4. The method according to claim 1 , further comprising:

acquiring a M-mode ultrasonograph of the viscoelastic medium and selecting a position to detect the elasticity of the viscoelastic medium according to the M-mode ultrasonograph; or

using a two-dimensional or three-dimensional ultrasonic image of the viscoelastic medium to select a position to detect the elasticity of the viscoelastic medium.

5. The method according to claim 1 , further comprising:

detecting a verticality between the ultrasonic transducer probe and the viscoelastic medium; and

in response to the verticality satisfying a preset condition, detecting the elasticity of the viscoelastic medium.

6. A device for detecting an elasticity of a viscoelastic medium, comprising:

a vibrator producing a vibration;

an ultrasonic transducer probe driven by the vibrator with the vibration so as to produce an elastic wave to be propagated in the viscoelastic medium;

a control apparatus connected with the ultrasonic transducer probe and the vibrator respectively, and configured to control the ultrasonic transducer probe to transmit an ultrasonic wave to the viscoelastic medium and to collect through the ultrasonic transducer probe an ultrasonic echo returned from the viscoelastic medium and corresponding to the transmitted ultrasonic wave, the control apparatus being further configured to select an effective ultrasonic echo from the ultrasonic echo according to a duration of the vibration and physical parameters of the viscoelastic medium, and to calculate a propagation velocity of the elastic wave in the viscoelastic medium according to the effective ultrasonic echo, and to calculate the elasticity of the viscoelastic medium according to the propagation velocity of the elastic wave, wherein the ultrasonic transducer probe stops vibrating and the elastic wave is propagated in the viscoelastic medium at a moment corresponding to the effective ultrasonic echo; and

a pressure sensor array mounted between and contacted with the ultrasonic transducer probe and the vibrator,

wherein the control apparatus further comprises a pressure signal collecting circuit connected with one of a computer, a microprocessor and a microcontroller through a communication interface, and wherein the control apparatus detects with the pressure sensor array a pressure applied to the viscoelastic medium by the ultrasonic transducer probe and a verticality of the ultrasonic transducer probe relative to the viscoelastic medium, and wherein the control apparatus is further configured to start to detect the elasticity of the viscoelastic medium in response to the detected pressure and the detected verticality satisfying preset conditions.

7. The device according to claim 6 , wherein the control apparatus comprises one of a computer, a microprocessor and a microcontroller, as well as an ultrasonic transmitting and receiving circuit connected with the one of the computer, the microprocessor and the microcontroller through a communication interface.

8. The device according to claim 6 , wherein the control apparatus comprises a triggering key implemented by a hardware or a software for starting to detect the elasticity of the viscoelastic medium.

9. The device according to claim 6 , wherein the control apparatus is further configured to start to detect the elasticity of the viscoelastic medium according to a verticality between the ultrasonic transducer probe and the viscoelastic medium.

10. The device according to claim 6 , further comprising an ultrasonic diagnostic equipment connected with the control apparatus for selecting a position to detect the elasticity of the viscoelastic medium.

11. The device according to claim 6 , further comprising a state indicating device for indicating a current working state of the device.

12. The device according to claim 6 , further comprising a mechanical arm for supporting an ultrasonic probe consisting of the ultrasonic transducer probe and the vibrator.