Formulas Flashcards
Wavelength
Wavelength = propagation speed divided by frequency
Frequency
Frequency = prop speed divided by wavelength
Prop speed
Prop speed = frequency x wavelength
Impedance
Z = density x prop speed
Pulse duration
PD = number of cycles x period
Duty factor
DF = PD divided by PRP
Spatial pulse length
SPL = number of cycles x wavelength
Axial resolution
AR = 1/2SPL
Attenuation coefficient
AC = 1/2f
Total attenuation
TA= AC x path length
Half intensity depth
HID = 6/f
Rayleigh scatter
F^4
Intensity transmission coefficient
ITC = 1- IRC
Intensity reflection coefficient
IRC = (z2 - z1/z2 + z1)^2
Beam uniformity ratio
BUR = SP/SA
Temporal average
TA = pulse average x duty factor
Quality factor
Q factor = operating frequency divided by bandwidth
Frame rate
FR = PRF / lines per frame
Range equation
Distance to reflector = prop speed x round trip time divided by 2
D = c x t/2
Number of shades of gray
2^#of bits
Hydrostatic pressure
HP = density x height of column of blood x gravity
Continuity/flow equation
Q = VA Flow = velocity x area
Bernoulli’s principle
(P1-P2)/4v^2
Poiseuilles law
Q = (P1-P2)/(8Ln/piR^4)
Pressure difference divided by resistance
Resistance is 8 x length of vessel x viscosity divided by pi x radius of vessel to the fourth power
Resistance
8Ln/piR^4
Intensity
I = P/A Intensity = power / area
