An ultrasonic imaging method, suitable for the ultrasonic imaging system including a transmitting beamformer, a receiving beamformer, a plurality of transducer elements corresponding to a plurality of receiving channels and selectively connected to the transmitting beamformer or the receiving beamformer, and a controller circuit connected to the transmitting beamformer and the receiving beamformer, the ultrasonic imaging method comprising:
- configuring the controller circuit to, in a transmitting process, control the transmitting beamformer to transmit a plurality of ultrasonic sound signals that focus at scan depths through the transducer elements, wherein the receiving beamformer includes:
- a common fine delay beamformer including a plurality of channel groups, each of the plurality of channel groups corresponding to a part of the receiving channels and including a plurality of fine delay circuits and a first summation unit;
- a plurality of coarse delay beamformers respectively corresponding to the output beam signals and each including:
- a plurality of coarse delay circuits connected to multiple ones of the first summation unit;
- and
- a second summation unit connected to the coarse delay circuits;
- configuring the transducer elements to, in a receiving process, receive echo signals of the ultrasonic sound signals and send the echo signals to the channel groups;
- configuring the controller circuit to apply a common fine delay set to the echo signals by controlling the common fine delay beamformer;
- configuring multiple ones of the first summation unit to perform first summation operations on the corresponding echo signals to generate a plurality of first summation signals;
- configuring the controller circuit to apply a plurality of compensated coarse delay sets to the first summation signals by controlling the coarse delay beamformers;
- configuring multiple ones of the second summation unit to perform second summation operations on the corresponding delayed first summation signals, so as to generate a plurality of output beam signals;
- configuring the controller circuit to perform a multi-beam calculation process to determine the common fine delay set, wherein the multi-beam calculation process includes:
- obtaining a plurality of ideal delays for each of the output beam signals according to the scan depths and a hardware configuration of the plurality of transducer elements;
- obtaining a plurality of coarse delays for each channel group according to an equation (1):
- CoarseDelay (k)≤min{BeamformDelay (1), . . . , BeamformDelay (n)} equation (1),
- wherein n is a channel number of the receiving channel of a kth one of the channel groups, CoarseDelay (k) is the coarse delay of the kth one of the channel groups, BeamformDelay (n) is the ideal delay of the nth one of the receiving channels, and k and n are integers equal to or larger than 1;
- obtaining a plurality of fine delays of the plurality of receiving channels according to an equation (2):
- FineDelay (n)=BeamformDelay (n)−CoarseDelay (k) equation (2),
- wherein FineDelay (n) is the fine delay of the nth of the receiving channels;
- obtaining the common fine delay set according to an equation (3):
- CommonFineDelay (n)=f(FineDelayBeam_1 (n), FineDelayBeam_2 (n), . . . , FineDelayBeam_x (n)), where min(FineDelayBeam_1 (n), FineDelayBeam_2 (n), . . . , FineDelayBeam_x)≤f(FineDelayBeam_1 (n), FineDelayBeam_2 (n), . . . , FineDelayBeam_x)≤max(FineDelayBeam_1 (n), FineDelayBeam_2 (n), . . . , FineDelayBeam_x) equation (3),
- wherein CommonFineDelay (n) is a common fine delay of nth one of the receiving channels, FineDelayBeam_1 (n), FineDelayBeam_2 (n), . . . , FineDelayBeam_x (n) are the fine delays of nth one of the receiving channels of first to xth ones of the output beam signals, and f(.) is a linear function or non-linear function, x is an integer equals to or larger than 1, the common fine delay set includes CommonFineDelay (1), CommonFineDelay (2), . . . , CommonFineDelay (j), and j is a quantity of the receiving channels.