DMS 200 - 1-7 REVIEW - EQUATIONS QUIZ
A wave that repeats itself 4 times in one microsecond has a period of?
.25 us. or ¼ us 4 times in one microsecond is 4 MHz - invert Or, 4 cycles in one us has a period of ¼ us
What is the time for the following values? Time = ??? Rate = 2 m/s Distance = 4 meters
2 m/s D = R x T solve for T = D / R Time = D / R 4/2 = 2
What is the rate (velocity) for the following values? Rate = ??? Time = 2 us Distance = 4 mm
2 mm/us Rate = Distance / Time 4/2 = 2
What is the period of a wave with a frequency of 3 Hz?
3 inverted = 1/3 second
What is the rate (velocity) for the following values? Rate = ??? Time = 2 sec Distance = 6 meters
3 m/s D = R x T solve for R = D / T Rate = Distance / Time = 6/2 = 3
What is the distance traveled for the following values? Rate = 1540 m/s Time = 2 sec Distance = ???
3080 meters D = R x T R = D / T alternate equation solving for Rate T = D / R alternate equation solving for Time
What is the depth to the reflector for the following values? Rate = 4 m/s Time =2 sec Depth = ???
4 meters (D = R x T) / 2 4x2 = 8 / 2 = 4
A wave that repeats itself 4 times in one microsecond has a frequency of?
4 times in one us is the frequency = 4MHz or, the period is ¼ of a us
What is the distance traveled for the following values? Rate = 1.54 mm/us Time = 3 us Distance = ???
4.62 mm D = R x T
What is the time for the following values? Time = ??? Rate = 1 m/s Distance = 5 meters
5 m/s D = R x T solve for T = D / R Time = D / R 5/1 = 5
What is the depth for the following values? Rate = 3 mm/us Time = 4us Depth = ???
6 mm (D = R x T) / 2 3x4 = 12 12/2 = 6
If the incident angle of a beam is 60 degrees and it reflects off of a specular reflector, the reflected angle will be _____________ degrees.
60 DEGREES. LUEZ'S LAW (LAW OF REFLECTION)
What is the attenuation coefficient of a 10MHz pulse?
AC = ½ frequency AC = 10MHz / 2 = 5 db/cm
What is the attenuation coefficient of a 4MHz pulse?
AC = ½ frequency AC = 4MHz / 2 = 2 db/cm
What is the duty factor for a pulse that has a pulse duration of 2us and a pulse repetition period of 10us?
DF = PD / PRP DF = 2us / 10us = .2 or 20%
What is the duty factor for a pulse that has a pulse duration of 4us and a pulse repetition period of 10us?
DF = PD / PRP DF = 4us / 10us = .4 or 40%
What is the depth of a reflector if a pulse travels for 2us (round trip) in soft tissue?
Depth = rate x time / 2 = 1.54 x 2 = 3.08 3.08/2 = 1.54mm
If a wave is pulsed with a duty factor of .10, an idle time of 4 us, a wavelength of 3mm, period of 1/1,000,000 of a second, and a resistance of 7 rayls, what is the frequency of the wave?
F = 1/P = 1,000,000 / 1 = 1 MHz
What is the frequency of a wave if the period is 2 seconds?
F = 1/P = ½ or (.5) INVERT
What is the frequency of a wave if the period is 1 second?
F = 1/P F = 1 / 1 = 1 hz INVERT
What is the half value layer of 10 MHz pulse?
HVL = 3/AC AC = ½ FREQ AC = 10/2 = 5 db/cm HVL = 3/5 cm deep
What is the half value layer of 6 MHz pulse?
HVL = 3/AC AC = ½ FREQ AC = 6/2 = 3 db/cm HVL = 3/3 = 1 cm deep
What is the half value layer of 9 MHz pulse?
HVL = 3/AC AC = ½ FREQ AC = 9/2 = 4.5 db/cm HVL = 3 / 4.5 cm deep
What is the impedance of a wave traveling through liver tissue with a speed of 1555 and a density of 1050?
IMPEDANCE = DENSITY x SPEED Z=pc z = 1050 kg/m3 x 1555m/s Z = 1,632,750 rayls, or 1.63 x 10(6) rayls
What is the intensity reflection coefficient (IRC) if a pulse has an intensity transmission coefficient (ITC) of .15?
INCIDENT SOUND (1) = IRC + ITC IRC = 1 - ITC IRC = 1 - .15 IRC = .85
What is the intensity reflection coefficient (IRC) if a pulse has an intensity transmission coefficient (ITC) of .35?
INCIDENT SOUND (1) = IRC + ITC IRC = 1 - ITC IRC = 1 - .35 ITC = .65
What is the intensity transmission coefficient (ITC) if a pulse has an intensity reflection coefficient (IRC) of .25?
INCIDENT SOUND (1) = IRC + ITC ITC = 1 - IRC ITC = 1 - .25 ITC = .75
What is the intensity transmission coefficient (ITC) if a pulse has an intensity reflection coefficient (IRC) of .35?
INCIDENT SOUND (1) = IRC + ITC ITC = 1 - IRC ITC = 1 - .35 ITC = .65
What is the change in intensity if amplitude decreases by half?
INTENSITY = AMPLITUDE SQUARED INTENSITY = 1/2(squared) = 1/4
What is the change in power if amplitude decreases by half?
INTENSITY = AMPLITUDE SQUARED INTENSITY = 1/2(squared) = 1/4
What is the change in intensity if amplitude increases 3x?
INTENSITY = AMPLITUDE SQUARED INTENSITY = 3X (squared) = 9x
What is the change in power if amplitude increases 3x?
INTENSITY = AMPLITUDE SQUARED INTENSITY = 3X (squared) = 9x
What is the intensity of a 100 watt beam that is 2cm square?
INTENSITY = POWER / AREA INTENSITY = 100 watts / 2cm sq = 50 watts / cm squared
What is the intensity of a 50 watt beam that is 5cm square?
INTENSITY = POWER / AREA INTENSITY = 50 watts / 5cm sq = 10 watts / cm squared
At the boundary of two mediums, medium "A" has an impedance of 2 rayls and medium "B" has an impedance of 4 rayls. What is the intensity reflection coefficient?
IRC = [(Z2 - Z1) / (Z2 + Z1) Squared IRC = [(4 - 2) / (4+2)] sqauared IRC = (2/6) squared = 1/3 squared = 1/9 = .11
At the boundary of two mediums, medium "A" has an impedance of 4 rayls and medium "B" has an impedance of 6 rayls. What is the intensity reflection coefficient?
IRC = [(Z2 - Z1) / (Z2 + Z1) Squared IRC = [(6 - 4) / (6+4)] squared IRC = (2/10) squared = 1/5 squared = 1/25 =.04
A beam enters a patient at 45 degrees and propagates first through the liver before entering a layer of fat. Will the angle of transmission be positive or negative?
NEGATIVE. FAST TO SLOW = NEGATIVE. SLOW-FAST=POSITIVE
A pulse that takes 3 cycles to complete with a frequency of 3 Hz has a pulse duration of
PD = # Cycles x Period PD = # CYCLES / FREQUENCY = 3 cycles / 3Hz = 1
Pulse duration plus idle time equals _____________________
PRP
What is the pulse repetition period (PRP) of a pulse with a pulse repetition frequency (PRF) of 5Hz?
PRP = 1/PRF PRP = 1/5 sec
If the pulse has a pulse duration of 2us and an idle time of 8us, what is the pulse repetition period (PRP)?
PRP = PD + IDLE TIME PRP = 2us + 8us PRP = 10us
The pulse duration of a pulse with a period of 2us and 4 cycles in the pulse is
Pd = #cycles x period = 4cycles x 2us = 8us
What is the frequency of a wave with a period of .5 seconds?
Period = .5 period = ½ frequency (inverted) = 2 Hz
What is the frequency of a wave with a period of 2 seconds?
Period = 2 seconds period inverted = ½ Hz
A wave that travels to the reflector and back in 4 us through soft tissue will have a time to the reflector of _________ us
Round trip time / 2 = 4us / 2 (one-way trip, half the distance) = 2us
What is the speed in medium 2 if the sine of the incident angle is 1, the sine of the refracted angle is .5, and the speed in medium 1 is 4mm/us?
SINE REF = SPEED MED 2 .5 = MED 2 .5 x 4mm = 1 x MED 2 SINE INCID= SPEED MED 1 1 = 4mmus 2mm/us = MED 2
What is the spatial pulse length of a 2 MHz pulse that completes 2 cycles in a pulse that propagates in soft tissue?
SPL = # CYCLES x SPEED / FREQUENCY SPL = 2 x 1.54 / 2MHz = 1.54
What is the spatial pulse length of a 4 MHz pulse that completes 3 cycles in a pulse that propagates in soft tissue?
SPL = # CYCLES x SPEED / FREQUENCY SPL = 3 x 1.54 / 4MHz = 1.54 SPL = 4.62 / 4 = 1.155
A pulse that travels in soft tissue has a spatial pulse length of 4mm. The frequency is unknown, but the number of cycles per pulse is 8. What is the wavelength?
SPL = # CYCLES x WAVELENGTH WAVELENGTH = SPL / # CYCLES WAVELENGTH = 4mm / 8 cycles = .5 mm
What is the spatial pulse length of a pulse that has a wavelength of 2mm and completes 3 cycles per pulse?
SPL = WAVELENGTH x # OF CYCLES = 2mm x 3 cycles = 6mm
What is the spatial pulse length of a pulse that has a wavelength of 4mm and completes 2 cycles per pulse?
SPL = WAVELENGTH x # OF CYCLES = 4mm x 2 cycles = 8mm
If the incident angle of a beam is 60 degrees and it reflects off of a non-specular reflector, the reflected angle will be _____________ degrees.
UNKNOWN. LUEZ'S LAW ONLY APPLIES TO SPECULAR REFLECTORS
What is the frequency of a wave that propagates at a speed of 1.5mm/us with a wavelength of 3mm?
WAVELENGTH = SPEED / FREQUENCY Frequency = Speed / Wavelength speed = 1.5mm/us / 3mm = 1/2MHz
What is the speed of a wave that has a wavelength of 5mm and a frequency of 2 MHz?
WAVELENGTH = SPEED / FREQUENCY SPEED = WAVELENGTH x FREQ speed = 5mm x 2MHz 10mm/us
What is the wavelength of a wave that has a speed of 5 m/s and a frequency of 5 Hz?
Wavelength = speed / frequency = 5 m/s / 5Hz = 1 meter NOTE: VELOCITY AND SPEED MAY BE INTERCHANGED SOMETIMES
A wave that has a speed of 7 mm/us and a frequency of 3.5 MHz has a wavelength of:
Wavelength = speed / frequency = 7 mm/us / 3.5MHz = 2 mm
A wave propagates through adipose (fat) tissue with a pulse duration of 3us, density of 900, and a duty factor of .5 percent. If the wave is pulsed with a duty factor of .75 and uses 3 cycles to complete the pulse, what is the new impedance?
Z=pc = 900 kg/m3 x 1460 m/s Z = 1,314,000 rayls, or 1.31 x 10(6) rayls
What is the period of a wave with a frequency of .5 Hz?
½ frequency inverted = 2/1 = 2 seconds
