Deadbeat IIR based MTI filtering for color flow imaging systems

A deadbeat second order IIR (infinite impulse response) filtering procedure, which effectively has no undesirable transient effects (severe ringing associated to recursive IIR filters) is introduced. Thus an IIR based MTI (moving target indicator) filtering approach with steady state frequency response much more superior to that of comparable nonrecursive finite impulse response (FIR) filters, can be used for pulsed ultrasound color flow imaging. Although traditionally used FIR filters such as single and double cancellers virtually have no transient problem, but their steady state frequency characteristics are much more inferior to that of comparable IIR filters. Thus using this deadbeat IIR MTI filtering approach will allow detection of much lower velocity flow information, as the authors demonstrate using measured data from a flow phantom. The deadbeat performance of this IIR filter is also shown using simulated sinusoidal data. This filter can be cascaded also to produce higher order deadbeat IIR MTI filters having even faster stop band roll off