Ultrasound Relation Cross Scans

Impedance Reflection Three-Row Scan

Impedance contrast sets the pressure reflection ratio. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Impedance contrast sets the pressure reflection ratio

The left impedance stays fixed while the right impedance changes the numerator and denominator.

R=ZR−ZLZR+ZLR={Z_R-Z_L\over Z_R+Z_L}
Impedance ratio rowThe reflected pressure is bound to the ratio.incidentreflectedtransmittedleft 2 raylright 6 raylR 1/2in 6 Paback 3 Pathrough 9 PaI back 9 W/m^2

Three right impedances give three reflection ratios

The incident pressure is fixed; reflected pressure follows the checked ratio.

ZLZRRpr2413226123210234\begin{array}{c|c|c|c}Z_L&Z_R&R&p_r\\2&4&\frac{1}{3}&2\\2&6&\frac{1}{2}&3\\2&10&\frac{2}{3}&4\\\end{array}

The middle row has one-half pressure reflection

The displayed pressure echo is not free; it is the incident pressure times the checked ratio.

6⋅12=36\cdot\frac{1}{2}=3
Pressure echo from impedanceThe sign and amplitude are checked together.incidentreflectedtransmittedleft 2 raylright 6 raylR 1/2in 6 Paback 3 Pathrough 9 PaI back 9 W/m^2