# Physics - Formulas

## 26 terms · Ultrasound Physics

λ = c / f

f = 1/T

T = 1/f

### Attenuation Coefficient

atten coeff = ½ f

or

f/2

PRP (ms) = 1/PRF

PRF (Hz) = 1/PRP

### Spatial Pulse Length

SPL (mm) = λ * n

n = number of cycles in a pulse

### Pulse Duration

PD (µs) = n/f

n = number of cycles in a pulse

### Duty Factor

DF (%) = PD/PRP

*it is unit less!

### Amplitude

max variation - mean value (dB)

### Power

P (W) or (mW) = A^2

### Intensity

I = P (W)/area (cm^2)

### Total Attenuation

TA (dB) = atten coef (dB/cm/MHz) * d (cm)

*d = distance

### Intensity Reflection Coefficient

IRC = [(Z₂-Z₁)/(Z₂+Z₁)]²

### The Range Equation

d (mm) = ½ ct

* t = pulse round trip time

/

### Impedance

Z (rayls) = ρ * c

* ρ = rho > density

ar = SPL/2

lr = beam width

### Operational Frequency

fo (MHz) = c (mm/µs)/2*th (mm)

*fo = operational (or resonant) frequency
*c = propagation speed of the transducer
*th = thickness of the element

### Q-factor

Q = fo/bandwidth (MHz)

*fo = operational (or resonant) frequency

### Imaging Depth max

pen (cm) * PRF (kHz) <= 77 (cm/ms)

pen (cm) n LPF * FR (Hz) <= 77,000 cm/s

### PRF (Hz) with FR

PRF (Hz) = n LPF FR (Hz)

77,000 cm/s / Imaging Depth (cm)

NL (kHz) = PRF/2

### Doppler shift

2 Fo V * Cosθ / C

Fe - Fo

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