Ultrasonic measurement method, ultrasonic measurement apparatus, and program storage device readable by machine
An ultrasonic measurement method includes irradiating an object to be measured with an ultrasonic wave, acquiring a reflection wave from the object, calculating at a processor an acoustic impedance in a depth direction of the object from the reflection wave, and estimating and outputting a thickness of the object based upon an inflection point determined by second-order differentiation of the acoustic impedance.
1. An ultrasonic measurement method comprising:
irradiating an object to be measured with an ultrasonic wave;
acquiring a reflection wave from the object,
calculating at a processor an acoustic impedance in a depth direction of the object from the reflection wave; and
estimating and outputting a thickness of the object based upon an inflection point determined by second-order differentiation of the acoustic impedance.
2. The ultrasonic measurement method as claimed in claim 1 ,
wherein the object to be measured is an outermost layer of a multilayer structure, and
wherein a distance from a first inflection point that first exceeds a predetermined threshold level in the depth direction to a next inflection point located deeper than the first inflection point and at which a sign of a curvature of a rate of change of the acoustic impedance is flipped from negative to positive, is output as the thickness.
3. The ultrasonic measurement method as claimed in claim 2 ,
wherein the first inflection point and the next inflection point are determined by a second-order differentiation filtering process.
4. The ultrasonic measurement method as claimed in claim 1 , further comprising:
outputting an evaluation value of stiffness or elasticity of the object based upon at least one of the thickness and a calculation value of the acoustic impedance.
5. The ultrasonic measurement method as claimed in claim 1 , further comprising:
generating and outputting an image representing a characteristic of the object to be measured based upon a distribution of the acoustic impedance in the depth direction.
6. The ultrasonic measurement method as claimed in claim 1 ,
wherein the object to be measured is a biological membrane.
7. The ultrasonic measurement method as claimed in claim 1 ,
wherein the object to be measured is human skin, and an estimation value of a skin age is output based upon the thickness.
8. A program storage device readable by a machine comprising:
a memory that stores an ultrasonic measurement program, the ultrasonic measurement program causing the machine to execute procedures of
acquiring a reflection signal of an ultrasonic wave reflected from an object to be measured;
calculating an acoustic impedance in a depth direction of the object from the reflection signal;
estimating a thickness of the object based upon an inflection point determined by a second derivative of the acoustic impedance; and
outputting an estimation value of the thickness.
9. An ultrasonic measurement apparatus: comprising:
an ultrasonic measuring instrument configured to irradiate an object to be measured with an ultrasonic wave and receive a reflection wave from the object; and
a processor that calculates an acoustic impedance in a depth direction of the object based upon the reflection wave, and outputs an estimation value of a thickness of the object based upon an inflection point determined from a second derivative of the acoustic impedance.
10. The ultrasonic measurement apparatus as claimed in claim 9 ,
wherein the processor outputs an evaluation value of stiffness or elasticity of the object based upon at least one of the thickness and a calculation value of the acoustic impedance.
11. The ultrasonic measurement apparatus as claimed in claim 9 , further comprising:
a display device,
wherein the processor generates an image representing a characteristic of the object to be measured based upon a distribution of the acoustic impedance in the depth direction, and
the display device displays the image generated by the processor.