Retrospective dynamic transmit focusing.
Dynamically-focused on receive, real-time array systems exhibit image degradation far from the focal zone of the fixed transmit lens. A retrospective filtering technique reducing the effects of the fixed transmitter is presented. The filter deconvolves the defocused transmit pattern producing a new in-focus transmit/receive image, where the filter coefficients are derived with a least-squares method. Experimental results are presented for a 128 channel array system showing the method's performance. A proposed architecture for real-time filtering is also discussed.
Freeman
S
S
Electrical Engineering and Computer Science Department, University of Michigan, Ann Arbor 48109, USA.
Li
P C
PC
O'Donnell
M
M
D004867:Equipment Design; D005374:Filtration / Q000295:instrumentation; D005583:Fourier Analysis; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation*; D016018:Least-Squares Analysis; D008953:Models, Anatomic; D014159:Transducers; D014463:Ultrasonography / Q000295:instrumentation*