Equations & Units Flashcards
Frequency:
- Equation?
- Units?
- f = 1/T
- Hz, cycles/sec, per second
Period:
- Equation?
- Units?
- T = 1/f
- seconds
Pressure:
- Equation?
- Units?
- pressure = force/area
- Pascals (Pa)
Wavelength:
- Equation?
- Units?
- wavelength = c/f
- mm
Pulse Repetition Period (PRP):
- Equation?
- Units?
- PRP = 1/PRF
- seconds
Pulse Repetition Frequency (PRF):
- Equation?
- Units?
- PRF = 1/PRP
- Hz
Intensity:
- Equation?
- Units?
- Intensity = power/beam area
- mW/cm^2
Beam Uniformity Factor (BUF):
- Equation?
- Units?
- BUF = SP/SA
- No units
10 dB:
- Equation?
- Units?
- dB = 10 log (I/I original); dB = 10 log (P/P original); dB = 20 log (A/A original)
- No units
3 dB:
- Equation?
- Units?
- Use step method (either half (negative) or double (positive))
- mW/cm^2
Half Value Layer Thickness (HVLT):
- Equation?
- Units?
- HVLT = 3 dB/f x AC
- cm
Impedance:
- Equation?
- Units?
- Impedance = density x velocity
- Rayls (Z) or rayls (z)
Intensity Reflection Coefficient (IRC):
- Equation?
- Units?
- IRC = Ir/Ii
- %
Intensity Transmission Coefficient (ITC):
- Equation?
- Units?
- ITC = It/Ii
- %
Total Attenuation (TA):
- Equation?
- Units?
- TA = AC x f x PL
- dB
Density:
- Equation?
- Units?
- Density = kg/m^3
- kg/m^3
Incident Intensity:
- Equation?
- Units?
- Ii = Ir + It;
100% = %R + %T - %
%R:
- Equation?
- Units?
- %R = [ z2 - z1/z2 + z1]^2
- No units
Round Trip:
- Equation?
- Units?
- RT = (%T)^2
- %
Duty Factor (DF):
- Equation?
- Units?
- DF = PD/PRP
- No units
Spatial Pulse Length (SPL):
- Equation?
- Units?
- SPL = wavelength x # cycles in pulse
- mm
Axial Resolution:
- Equation?
- Units?
- Axial Resolution = SPL/2
- mm
Frame Time:
- Equation?
- Units?
- Frame Time = (13 us/cm) x (image depth (cm)/line) x (# line/frame)
- us/frame
Frame Rate (or Frame Frequency):
- Equation?
- Units?
- Frame Rate = # of frames/frame time
- MHz
Q Factor (QF):
- Equation?
- Units?
- QF = main frequency/bandwidth
- No units
Bandwidth (BW):
- Equation?
- Units?
- BW = max - min
- MHz
Near Zone Length (NZL):
- Equation?
- Units?
- NZL = (diameter ^2 x frequency)/(6 mm/us); NZL = (diameter^2)/(4 x wavelength)
- mm
Divergence of an angle:
- Equation?
- Units?
- sin = (1.2 x wavelength)/diameter
- ???
Bernoulli’s equation:
- Equation?
- Units?
- Constant = P + 1/2pv^2 + pgh
- ???
Pulsatility Index (PI):
- Equation?
- Units?
- PI = (max - min)/average
- No units
Resistivity Index (RI):
- Equation?
- Units?
- RI = (max - min)/max
- No units
Doppler Shift:
- Equation?
- Units?
- Doppler Shift = reflected frequency - transmitted frequency
- Hz
Doppler Equation:
- Equation?
- Units?
- fD = (2 x f original x v x cos)/c
- ???
Nyquist Limit:
- Equation?
- Units?
- Nyquist Limit = PRF/2
- MHz
Equation of Continuity:
- Equation?
- Units?
- Q = v x area;
A1 x v1 = A2 x v2 - ???
Parallel:
- Equation?
- Units?
- 1/ReQ = (1/R1) + (1/R2)
- No units
Law of Hemodynamics:
- Equation?
- Units?
- change of P = Q x R
- ???
Capacitance:
- Equation?
- Units?
- Capacitance = change in volume/change in time
- ???
Compliance:
- Equation?
- Units?
- Compliance = change in volume/change in pressure
- ???
Poiseuille’s Law:
- Equation?
- Units?
- Q = (pi x change in P x r^4)/8 x viscosity x L
- ???
Reynold’s Number (RN):
- Equation?
- Units?
- RN = (P x v x diameter)/viscosity
- No units
Resistance:
- Equation?
- Units?
- R = (8 x viscosity x L)/(pi x r^4)
- ???
Thermal Index (TI):
- Equation?
- Units?
- TI = W original/W deg
- No units
Mechanical Index (MI):
- Equation?
- Units?
- MI = (peak rare fractional pressure)/(f original)^1/2
- ???
Sensitivity:
- Equation?
- Units?
- Sensitivity = TP/(TP + FN)
- Fraction or %
Specificity:
- Equation?
- Units?
- Specificity = TN/(TN + FP)
- Fraction or %
Overall Accuracy (OA):
- Equation?
- Units?
- OA = (TP + TN)/ (TP + TN + FP + FN)
- Fraction or %
Positive Predictive Value (PPV):
- Equation?
- Units?
- PPV = [TP/(TP + FP)] x 100
- Fraction or %
