Chapter 1 Purple Book
In the clinical imaging, the wave length measures between:
0.1 to 0.8 mm
The typical range of frequency for diagnostic ultrasound is:
1-20 MHz
The duty factor for continuous wave ultrasound is
100%
What is the total amount of attenuation that occurs if a 6.0 MHz sound travels through 4 cm of soft tissue
12 dB
Which of the following is considered the speed of sound in soft tissue?
1540 m/s or 1.54 mm/microsecond
Which of the following would be considered ultrasonic?
1MHz
If the angle of incidence is 40°, what is the angle of transmission at the interface if medium one has a propagation speed of 1320 m/s and medium two heavy propagation speed of 1700 m/s?
>40°
The major component of attenuation is:
Absorption
As sound wave travels through the human body, the intensity of the soundwave decreases as a result of
All of the above (attenuation, absorption, and scattering)
The maximum value or minimum value of an acoustic a variable minus the equilibrium value of that variable describes the:
Amplitude
An increase in the pulse repetition frequency would lead to:
An increase in duty factor
All of the following are true of power except
As amplitude increases, power remains the same
What is defined as the ability of the ultrasound system to image structures that are positioned parallel to the sound beam as separate structures?
Axial resolution
Which of the following would have the highest propagation speed?
Bone
Areas of high pressure and density are referred to as:
Compressions
As imaging depth increases, the pulse repetition frequency must:
Decrease
The inertia of the medium describes its
Density
The percentage of time that the ultrasound system is producing pulses describes the
Duty factor
Which of the following is determined by the sound source only?
Frequency
The prefix "centi" denotes:
Hundredths
As imaging depth increased, pulse repetition period
Increases
If the pulse repetition frequency increases, the duty factor
Increases
What is essentially equal to the power of a wave divided by the area over which the power is distributed?
Intensity
What is the change in intensity of the power decreases by half?
Intensity is halved
Density and propagation speed are
Inversely related
What is the change in power if the amplitude triples?
It increases nine times
All of the following are true of wavelength except
It is equal to the period Divided by the frequency
Density is typically measured in
Kilograms per centimeter cubed
Transducers have material within them that, when electronically stimulated, produces ultrasound waves. This is most likely some form of:
Lead zirconate titanate
Which of the following would have the lowest propagation speed?
Lung tissue
Sound is technically a
Mechanical and longitudinal wave
Which of the following is an appropriate unit of measurement for propagation speed?
Millimeters per microsecond (mm/microsecond)
Micro denotes:
Millionth
Spatial pulse length can be calculated by:
Multiplying the number of cycles times the wavelength
The attenuation coefficient and soft tissue is equal to:
One half of the operating frequency
Pressure is typically expressed in:
Pascals
What is pressure measured in?
Pascals or pounds per square inch
If only the density of a medium is increased, Then the
Propagation speed with decrease
Which of the following is defined as only the active time?
Pulse duration
Which of the following is defined as the number of of ultrasound pulses emitted in one second?
Pulse repetition frequency
What is defined as the beginning of one pulse to the beginning of the next pulse, and therefore includes both the "on" and "off" time?
Pulse repetition period
The portion of the sound beam where the molecules are pulled apart describes an area of
Rarefactions
Damping of the sound beam:
Reduces the spatial pulse length
The change in the direction of the original sound wave that occurs when a sound interacts with two different tissue types that have a different propagation speed is referred to as:
Refraction
Which the following describes the amount of refraction that occurs at an interface?
Snell's law
Which of the following is described as the ability to resist compression and relates to the hardness of a medium?
Stiffness
All of the following are true of stiffness except:
Stiffness and propagation speed are indirectly associated
All of the following related to the strength of the soundwave except
Wavelength
Which of the following is described as the distance over which one cycle occurs?
Wavelength
Which of the following is determined by the sound source and medium?
Wavelength
