Test 1 Flashcards
What is the average velocity of ultrasound in soft tissue?
1.54 mm/microseconds
Propagation speed though a medium is primarily dependent on the _________________.
Stiffness
If sound waves of 3 MHz, 5 MHz, and 10 MHz are transmitted through the same section of liver, which signal would reach its target first?
Reflections from all three frequencies would have identical transit times.
In DMS, what is a period?
The time required to complete one wavelength
Which factor can NOT be controlled by the sonographer, either directly or indirectly?
A) propagation speed
B) amplitude
C) period
D) frequency
Propagation speed cannot be controlled by the sonographer
What is the unit for acoustic impedance?
Rayl’s
What is the unit for frequency?
Megaheartz
What is the unit for wavelength?
Millimeter
What is the unit for period?
Microsecond
What is the unit for power?
Watts
What is the unit for propagation speed?
Meter/Second
Rarefaction describes a region of _________ along the wave.
low pressure
What is the wavelength of a 3MHz ultrasound beam?
0.5 mm
When particle motion of a medium is parallel to the direction of the wave propagation, the wave being transmitted is called:
Longitudinal
In DMS, what is the period if the frequency is 2 MHz?
0.5 μm
What is 6 micrometers in scientific notation?
6 x 10^-6
What is equal to 5 mm in km?
0.000005
What describes sound propagations through a vacuum?
Sound cannot travel through a vacuum
What term describes the distance between the compression zones?
Wavelength
What is the formula for acoustic impedance?
density x propagation speed
(True/False)
Two waves that interact with each other will always cause destructive interference
False
Finish the Statement:
When frequency increases the resolution (blank)
and the ability of the beam to penetrate the medium (blank)
When frequency increases the resolution improves
and the ability of the beam to penetrate the medium decreases
Finish the Statement:
When frequency decreases, the period (blank)
and the wavelength (blank).
When frequency decreases, the period increases
and the wavelength increases
How many crystals are in a continuous wave transducer?
two
In diagnostic medical sonography, what will happen to the density if the frequency is doubled?
Density is not affected by frequency
What is the frequency if the period is 0.16 μs?
round to the nearest whole number
6 MHz
(Note: do not forget to write the unit)
What is one Hertz equal to per second?
One cycle per second
What is the term for any sound that is less than audible sound?
Infrasound
(True/False)
Wavelength and period are measuring the same portion of a wave just with different units.
True
What is the wavelength if you have a period of 0.25 microseconds?
round your answer to 2 decimal places
0.39 mm
(Note: do not forget to include the unit)
List the ultrasound velocity in biological tissues in order of slowest to fastest:
Tissues named: (not in order)
Bone
Fat
Blood
Air
Soft tissue
air, fat, soft tissue, blood, bone
What happens to the intensity if the amplitude is increased by a factor of 3?
The intensity would be increased by a factor of 9
What happens to the intensity if the area is decreased by a factor of two and all other factors are unchanged?
The intensity would be increased by a factor of 2
What type of relationship is there between wavelength and period?
Proportional
In DMS, what is amplitude?
Amount of change between the maximum and average
values for a variable.
In DMS, approximately how fast can sound travel in 20 μsec?
3 cm
3 kHz is equal to how many MHz?
0.003 MHz
(True/False)
Elasticity is a materials ability to be conformed when a force is applied to it.
False
(True/False)
Acoustic impedance is a property of the medium
True
Ultrasound is a sound with a frequency greater than (blank) Hz
20,000
Which of the following frequencies is in the ultrasound range?
A. 15 Hz
B. 15 kHz
C. 30,000 Hz
D. 15,000 Hz
C. 30,000 Hz
Name three acoustic variables
Particle motion
Density
Pressure
Frequency is the number of (blank) an acoustic variable goes through in a second
Cycles
The unit of frequency is (blank), abbreviated as (blank)
Hertz, (Hz)
Period is the (blank) that it takes for one cycle to occur
Time
Period decreases while (blank) increases
Frequency
Wavelength is the length of (blank) over which one cycle occurs
Space
Propagation speed is the speed with which a(n) (blank) moves through a medium
Wave
Wavelength is equal to (blank) divided by (blank)
propagation speed / frequency
The average propagation speed in soft tissues is ______m/s or ______mm/microsecond
1540 m/s or 1.54 mm/microsecond
Propagation speed is determined by the (blank)
Medium
Wavelength un soft tissues (blank) while frequency increases
Decreases
Sound is a (blank) , (blank) wave
Mechanical, longitudinal wave
From given values for propagation speed and frequency, (blank) can be calculated
Wavelength
Period equals (blank) divides by (blank)
of cycles divided by the frequency
Frequency = (blank) divided by (blank)
of cycles divided by the period
Phrase to remember scientific notation
Endless — Exto 12
Gossip — Giga 9
My — Mega 6
King — Kilo 3
Henry — Hecto 2
Died — Deka 1
By — base
Drinking — Deci -1
Chocolate — Centi -2
Milk — milli -3
My — micro -6
Nana — nano -9
Poisoned — pico -12
