ULTRASONIC DIAGNOSTIC APPARATUS, METHOD OF SIGNAL PROCESSING, AND NON-TRANSITORY COMPUTER READABLE MEDIUM

1 . An ultrasonic diagnostic apparatus comprising:

a transmitter circuit and receiver circuit configured to transmit an ultrasonic wave into a subject, based on a transmission condition, and receive an echo from inside the subject; and

a processing circuit configured to

cause the ultrasonic wave transmitted based on the transmission condition to propagate forward to obtain a transmission wave field,

cause a signal based on the echo to propagate backward to obtain a reception wave field by applying a weight function depending on a wavefront incident angle, and

perform correlation analysis between the transmission wave field and the reception wave field to generate an echo component.

2 . The ultrasonic diagnostic apparatus according to claim 1 , wherein the weight function is a function changing in accordance with a position in a depth direction.

3 . The ultrasonic diagnostic apparatus according to claim 2 , wherein the weight function is a function in which contribution of weight of a component the wavefront incident angle of which is small becomes relatively larger as depth becomes shallower.

4 . The ultrasonic diagnostic apparatus according to claim 3 , wherein the weight function is determined based on an imaginary reception aperture determined for each position in the depth direction.

5 . The ultrasonic diagnostic apparatus according to claim 1 , wherein

the processing circuit selects the signal based on the echo to be propagated backward in a process of generating the reception wave field, and

the processing circuit causes only the selected signal based on the echo to propagate backward to generate the reception wave field.

6 . The ultrasonic diagnostic apparatus according to claim 1 , wherein the processing circuit

obtains the transmission wave field by numerical analysis based on a wave equation, or

obtains the reception wave field by numerical analysis based on a wave equation.

7 . The ultrasonic diagnostic apparatus according to claim 1 , wherein the wavefront incident angle represents an incident direction of a wavefront when back propagation simulation is performed on the signal based on the echo.

8 . The ultrasonic diagnostic apparatus according to claim 1 , wherein the processing circuit causes the signal based on the echo to propagate backward to obtain the reception wave field, based on the weight function depending on a positional relation between a point for which an image is obtained and a point at which the echo has been received.

9 . A method of signal processing, the method comprising:

causing a transmission signal to propagate forward to obtain a transmission wave field;

causing a reception signal to propagate backward to obtain a reception wave field by applying a weight function depending on a wavefront incident angle representing an incident angle of a wavefront when back propagation simulation is performed on the reception signal; and

performing correlation analysis between the transmission wave field and the reception wave field to generate a signal.

10 . A non-transitory computer readable medium including programmed instructions, wherein the instructions, when executed by a computer, cause the computer to perform:

causing a transmission signal to propagate forward to obtain a transmission wave field;

causing a reception signal to propagate backward to obtain a reception wave field by applying a weight function depending on a wavefront incident angle representing an incident angle of a wavefront when back propagation simulation is performed on the reception signal; and

performing correlation analysis between the transmission wave field and the reception wave field to generate a signal.