Formulas

Question 1

Wavelength

Answer 1

Wavelength = propagation speed divided by frequency

Question 2

Frequency

Answer 2

Frequency = prop speed divided by wavelength

Question 3

Prop speed

Answer 3

Prop speed = frequency x wavelength

Question 4

Impedance

Answer 4

Z = density x prop speed

Question 5

Pulse duration

Answer 5

PD = number of cycles x period

Question 6

Duty factor

Answer 6

DF = PD divided by PRP

Question 7

Spatial pulse length

Answer 7

SPL = number of cycles x wavelength

Question 8

Axial resolution

Answer 8

AR = 1/2SPL

Question 9

Attenuation coefficient

Answer 9

AC = 1/2f

Question 10

Total attenuation

Answer 10

TA= AC x path length

Question 11

Half intensity depth

Answer 11

HID = 6/f

Question 12

Rayleigh scatter

Answer 12

F^4

Question 13

Intensity transmission coefficient

Answer 13

ITC = 1- IRC

Question 14

Intensity reflection coefficient

Answer 14

IRC = (z2 - z1/z2 + z1)^2

Question 15

Beam uniformity ratio

Answer 15

BUR = SP/SA

Question 16

Temporal average

Answer 16

TA = pulse average x duty factor

Question 17

Quality factor

Answer 17

Q factor = operating frequency divided by bandwidth

Question 18

Frame rate

Answer 18

FR = PRF / lines per frame

Question 19

Range equation

Answer 19

Distance to reflector = prop speed x round trip time divided by 2

D = c x t/2

Question 20

Number of shades of gray

Answer 20

2^#of bits

Question 21

Hydrostatic pressure

Answer 21

HP = density x height of column of blood x gravity

Question 22

Continuity/flow equation

Answer 22

Q = VA
Flow = velocity x area

Question 23

Bernoulli’s principle

Answer 23

(P1-P2)/4v^2

Question 24

Poiseuilles law

Answer 24

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

Question 25

Resistance

Answer 25

8Ln/piR^4

Question 26

Intensity

Answer 26

I = P/A
Intensity = power / area