Ultrasound image pickup apparatus
A transmitting beamformer performs convergence transmission that forms a transmission focus of an ultrasonic beam in a subject. A receiving beamformer comprises a virtual sound source method-based delay amount calculation part that obtains delay amount of a received signal with regarding the transmission focus as a virtual sound source, and a correction operation part that corrects the delay amount obtained by the virtual sound source method-based delay amount calculation part depending on position of imaging point. Delay amounts can be thereby obtained with good accuracy for imaging points in a wide area.
1. An ultrasonic imaging apparatus, comprising:
an ultrasonic element array in which a plurality of ultrasonic elements are arranged along a predetermined direction;
a transmitting beamformer that forms an ultrasonic beam to be transmitted into a subject by the ultrasonic element array;
a computer coupled to the ultrasonic element array and the transmitting beamformer; and
a controller coupled to the computer that generates image data using results outputted by a receiving beamformer,
wherein the transmitting beamformer performs convergence transmission that forms a transmission focus of the ultrasonic beam in the subject, and
wherein the computer is programmed to:
perform phasing of a plurality of received signals obtained by receiving the ultrasonic waves reflected in the subject with the ultrasonic element array by delaying received signals,
obtain delay amounts of the received signals based on the transmission focus as a virtual sound source, and
correct the obtained delay amounts based on positions of an imaging point,
wherein, the imaging point is outside a transmitted sonic wave region bound by two virtual lines projecting from different ultrasonic elements of the ultrasound element array and through the transmission focus,
wherein the computer is further programmed to:
correct a first delay amount (D 1 ) obtained for the imaging point using a second delay amount (D 2 ) obtained for a point located on one of the two virtual lines of the transmitted sonic wave region,
wherein the point located on one of the two virtual lines of the transmitted sonic wave region is a projection of the imaging point in a direction perpendicular to a sound axis of the ultrasonic beam.
2. The ultrasonic imaging apparatus according to claim 1 ,
wherein computer is further programed to:
obtain the second delay amount (D 2 ) by an operation using the first delay amount (D 1 ), and an angle θ formed by a line connecting the imaging point and the transmission focus, and a sound axis of the ultrasonic beam.
3. The ultrasonic imaging apparatus according to claim 1 , wherein the computer is further programed to: weight the first delay amount (D 1 ) and the second delay amount (D 2 ) with weight values and to add the first delay amount (D 1 ) and the second delay amount (D 2 ).
4. The ultrasonic imaging apparatus according to claim 3 , wherein the weight values used for the weighting vary depending on an angle θ formed by a virtual line connecting the imaging point and the transmission focus, and a sound axis of the ultrasonic beam.
5. The ultrasonic imaging apparatus according to claim 3 ,
wherein the computer is programmed to receive input of the weight values.
6. The ultrasonic imaging apparatus according to claim 1 ,
wherein the computer is programmed to:
store phased outputs, and
determine a phased output obtained from a received signal of the ultrasonic beam of a certain transmission, and synthesizes it with a phased output obtained from a received signal of the ultrasonic beam of another transmission.