An ultrasound transducer probe unit (201 300) having a body portion (301 903) and an array of transducers (404 701 906) in which the array of transducers is movable, relative to the body portion, in a reciprocating motion along a linear path, by an ultrasonic motor (610 800 908). Ultrasonic signals are transmitted and received by the array of transducers relative to a two dimensional section of a target which is to be imaged. The ultrasonic motor (610 800 908) is controlled to periodically stop the transducer movement at at least one stationary position along the linear path. Scanlines are acquired from the ultrasound signals which are transmitted and received by the array of transducers (404 701 906). The acquired scanlines include: plural B-mode scanlines acquired continuously during the reciprocating motion and plural sets of Doppler scanlines acquired when the array of transducers is stopped at the at least one stop position along the linear path. The linear path may be either straight or curvilinear. The ultrasonic motor may be either a rotary motor or linear motor.
