| 主权项 |
1. An ultrasound diagnostic apparatus comprising:
a transducer array; a transmission circuit for transmitting an ultrasonic beam from the transducer array toward a subject; a reception circuit for processing reception signals outputted from the transducer array having received ultrasonic echoes from the subject to produce reception data; an image producer for producing a B mode image based on the reception data obtained by the reception circuit; a controller for controlling the transmission circuit and the reception circuit to transmit ultrasonic beams composed of fundamental waves having a first frequency from the transducer array toward the subject and receive ultrasonic echoes having a second frequency, which is a harmonic component of the fundamental waves, to divide the B mode image into an intermediate region in a depth region where an intensity of the ultrasonic echoes having the second frequency is above a given value, a shallow region in positions shallower than the intermediate region, and a deep region in positions deeper than the intermediate region; a region-of-interest setting unit for setting in the B mode image produced by the image producer an intermediate region of interest in the intermediate region, a shallow region of interest in the shallow region and a deep region of interest in the deep region; and a sound speed calculator, the controller controlling the transmission circuit and the reception circuit to transmit ultrasonic beams having the first frequency with forming transmission focuses at a plurality of intermediate points set in and near the intermediate region of interest and receive ultrasonic echoes having the second frequency to obtain intermediate reception data for measuring a sound speed, to transmit ultrasonic beams having the second frequency with forming transmission focuses at a plurality of shallow points set in and near the shallow region of interest and receive ultrasonic echoes having the second frequency to obtain shallow reception data for measuring a sound speed, and to transmit ultrasonic beams having the first frequency with forming transmission focuses at a plurality of deep points set in and near the deep region of interest and receive ultrasonic echoes having the first frequency to obtain deep reception data for measuring a sound speed, the sound speed calculator calculating ambient sound speeds at the intermediate points based on the obtained intermediate reception data for measuring a sound speed, calculating ambient sound speeds at the shallow points based on the obtained shallow reception data for measuring a sound speed, and calculating ambient sound speeds at the deep points based on the obtained deep reception data for measuring a sound speed. |
