ARDMS Ultrasound Physics & Instrumentation Practice Exam

If only the density of a medium is increased, then the:

Propagation speed will decrease

Which of the following is described as the ability of an object to resist compression and relates to the hardness of a medium?

Stiffness

The prefix "centi" denotes:

Hundredths

Which of the following is defined as only the active time?

Pulse duration

In clinical imaging, the wavelength measures between:

0.1 to 0.8 mm

The duty factor for continuous wave ultrasound is:

100%

The inertia of the medium describes its:

Density

Which of the following would have the highest propagation speed?

Bone

The major component of attenuation is:

Pulse repetition frequency

Which of the following is determined by the sound source only?

Frequency

Micro denotes:

Millionth

Which of the following would be considered ultrasonic?

1 MHz

The typical range of frequency for diagnostic ultrasound imaging is:

1 to 20 MHz

What is the total amount of attenuation that occurs if a 6.0-MHz sound beam 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

If the angle of incidence is 40°, what is the angle of transmission at the interface if medium 1 has a propagation speed of 1320 m/s and medium 2 has a propagation speed of 1700 m/s?

>40°

The maximum value or minimum value of an acoustic variable minus the equilibrium value of that variable describes the:

Amplitude

An increase in 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

As a sound wave travels through the human body, the intensity of the sound wave decreases as a result of:

Attenuation Absorption Scattering Attenuation is a decrease in the amplitude, power, and intensity of the sound beam as sound travels through tissue. There are three mechanisms of attenuation: absorption, reflection, and scattering.

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

Areas of high pressure and density are referred to as:

Compressions

As imaging depth increases, the pulse repetition frequency must:

Decrease

The percentage of time that the ultrasound system is producing pulses of ultrasound describes the:

Duty factor

As imaging depth increases, pulse repetition period:

Increases

If pulse repetition frequency increases, then 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 if 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

Spatial pulse length can be calculated by:

Multiplying the number of cycles times the wavelength

The attenuation coefficient in soft tissue is equal to:

One half of the operating frequency

Pressure is typically expressed in:

Pascals

Which of the following is defined as the number of ultrasound pulses emitted in 1 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 pulse repetition period is the time from the start of one pulse to the start of the next pulse, and therefore, it includes the "on" (or transmit) and "off" (or listening) times

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?

Rarefaction Rarefaction is an area in the sound wave where the molecules are spread wider apart.

Damping of the sound beam:

Reduces the spatial pulse length

The change in the direction of the original sound wave that occurs when sound interacts with two different tissue types that have a different propagation speed is referred to as:

Refraction Refraction is the change in direction of the transmitted sound beam that occurs with oblique incidence and dissimilar propagation speeds.

Which of the following describes the amount of refraction that occurs at an interface?

Snell's law Refraction is a redirection of the transmitted sound beam. Snell's law describes the angle of transmission at an interface based on the angle of incidence and the propagation speeds of the two media.

All of the following are true of stiffness except:

Stiffness and propagation speed are indirectly associated Stiffness and propagation speed are directly related: the stiffer the medium, the faster the propagation speed.

All of the following relate to the strength of the sound wave except:

Wavelength

Which of the following is determined by the sound source and medium?

Wavelength

Which of the following is described as the distance over which one cycle occurs?

Wavelength Wavelength is distance over which one cycle occurs, or the distance from the beginning of one cycle to the end of the same cycle.

Which of the following is an appropriate unit of measurement for propagation speed?

millimeters per microsecond (mm/μs)

What is pressure measured in?

pascals or pounds per square inch