Signal processing device, ultrasound diagnostic apparatus, and signal processing method

A signal processing device which uses a first signal waveform of ultrasound reflected from an object in a first compressed state and a second signal waveform of ultrasound reflected from the object in a second compressed state and calculates an elasticity of the object affected by a change in a compressed state, the device comprising:

• an approximated waveform generation unit which compresses or stretches and phase-shifts the second signal waveform by an elasticity and an initial phase difference related to a difference in angular frequencies being set and generates an approximated signal waveform approximated to the first signal waveform;
• a phase difference calculation unit which calculates a phase difference component in each time between the first signal waveform and the approximated signal waveform;
• a correlation calculation unit which calculates the elasticity and the initial phase difference between the first signal waveform and the approximated signal waveform according to a correlation between the each time and the phase difference component in the each time;
• a repeat determination unit which updates the approximated signal waveform by compressing or stretching and phase-shifting the approximated signal waveform by using the elasticity and the initial phase difference calculated by the correlation calculation unit until a predetermined condition is satisfied, and uses the updated approximated waveform and the first signal waveform to repeat processing by the phase difference calculation unit and the correlation calculation unit;
• and
• an elasticity calculation unit which calculates the elasticity on the basis of a cumulative value of the elasticity related to the compression repeatedly performed.

A signal processing method which uses a first signal waveform of ultrasound reflected from an object in a first compressed state and a second signal waveform of ultrasound reflected from the object in a second compressed state and calculates an elasticity of the object affected by a change in a compressed state, the method comprising:

• a phase difference calculation step which calculates a phase difference component in each time between the first signal waveform and the second signal waveform;
• a correlation calculation step which calculates an elasticity and an initial phase difference between the first signal waveform and the second signal waveform according to a correlation between the each time and the phase difference component in the each time;
• and
• an elasticity calculation step which calculates the elasticity on the basis of the elasticity.