ARDMS Ultrasound Physics & Instrumentation Practice Exam Part 1

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

Pulse duration Pulse duration is only the active time or "on" time.

The distance that a sound wave travels thru a medium in a second

Speed

What is described as the ability of an object to resist compression and related to the hardness of a medium?

Stiffness Stiffness is the ability of an object to resist compression and related to the hardness of a medium

The inertia of the medium describes its:

Density The inertia of a medium describes its density.

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

Frequency Frequency is determined by the sound source only.

Concentration of the energy of a sound beam

Intensity

In clinical imaging, the wavelength measures between:

0.1 to 0.8 mm In clinical imaging, the wavelengths measure between 0.1 and 0.8 mm.

Which of the following would be considered ultrasonic?

1 MHz

The typical range of frequency for diagnostic ultrasound imaging is:

1 to 20 MHz The typical range of frequency for diagnostic ultrasound is 1 to 20 MHz

What is the reciprocal of 10?

1/10

The duty factor for continuous wave ultrasound is:

100% The duty factor for continuous wave ultrasound is 100%.

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 The total amount of attenuation that occurs if a 6.0-MHz sound beam travels through 4 cm of soft tissue is 12 dB.

Which of the following is considered the speed of sound in soft tissue?

1540 m/s The average speed of sound in all soft tissue is considered to be 1540 m/s or 1.54 mm/μs.

When two numbers w a reciprocal relationship are multiplied the answer is?

1`

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° Pulse duration is only the active time or "on" time

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 freq would lead to?

An increase in duty factor An increase in pulse repetition period would lead to an increase in duty factor

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 Axial resolution is the ability to resolve reflectors that lie parallel to the beam as distinct echoes.

What organ has the highest propagation speed?

Bone Bone, which has a propagation speed of 4080 m/s, has the highest propagation speed

Areas of high pressure and density are referred to as:

Compressions Areas of high pressure and density are referred to as compression.

As imaging depth increases, the pulse repetition freq must?

Decreases As imaging depth increases, the PRF decreases

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

Duty factor The duty factor is the percentage of time the ultrasound system is producing a sound

The prefix "centi" denotes

Hundredths "Centi" denotes hundredths

As imaging depth increases, pulse repetition period:

Increases As imaging depth increases, the pulse repetition period increases.

If pulse repetition frequency increases, then the duty factor:

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 Intensity is essentially equal to the power of a wave divided by the area over which the power is distributed.

What is the change in intensity if the power decreases by half?

Intensity is halved If power is decreased by half, intensity is decreased by half.

Density and propagation speed are:

Inversely related Density and propagation speed are inversely related

Density and propagation speed are:

Inversely related Density and propagation speed are inversely related.

What is the change in power if the amplitude triples?

It increases nine times If amplitude triples, then power increases by nine times.

Density is typically measured in:

Kilograms per centimeter cubed 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 Transducers have material within them that, when electronically stimulated, produces ultrasound waves. These materials most likely consist of some form of lead zirconate titanate

What has the lowest propagation speed?

Lung tissue Lung tissue, which has a propagation speed 660 m/s has the lowest speed

Sound is technically a:

Mechanical and longitudinal wave

Micro denotes

Millionth Micro denotes millionth

Spatial pulse length can be calculated by:

Multiplying the number of cycles times the wavelength Spatial pulse length equals the number of cycles in the pulse multiplied by the wavelength.

The attenuation coefficient in soft tissue is equal to:

One half of the operating frequency The attenuation coefficient (in dB/cm) is the rate at which sound is attenuated per unit depth. It is equal to one half of the frequency (f/2) in soft tissue.

Pressure is typically expressed in:

Pascals Pressure is typically expressed in pascals

The time it takes a wave to vibrate a single cycle, or time from the sart of a cycle of the start of the next cycle

Period

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

Propagation speed will decrease If only the density of the medium is increased, then the propagation speed will decrease

The major component of attenuation is:

Pulse repetition frequency Absorption is the major component of attenuation.

Which of the following is defined as the number of ultrasound pulses emitted in 1 second?

Pulse repetition frequency Pulse repetition frequency is defined as the number of ultrasound pulses emitted in 1 second.

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 perio 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 Damping of the sound beam decreases 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.

What descries 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 relate to the strength of the sound wave except:

Wavelength Wavelength does not relate to the strength of the sound wave.

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

Wavelength Wavelength is determined by both the sound source and the medium.

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.

All of the following are true of power except:

a. As amplitude increases, power remains the same--FALSE b. Power is proportional to amplitude squared c. Intensity is proportional to power d. Power is measured in milliwatts Power decreases as amplitude decreases.

All of the following are true of stiffness except:

a. It is defined as the ability of an object to resist compression b. Stiffness and propagation speed are indirectly associated--FALSE c. Increasing stiffness increases propagation speed d. Stiffness may also be referred to as elasticity Stiffness and propagation speed are directly related: the stiffer the medium, the faster the propagation speed

All of the following are true of wavelength except:

a. It is determined by both the medium and the sound source b. It is equal to the period divided by the frequency--FALSE c. It is inversely related to frequency d. It is directly related to period Wavelength is equal to the propagation speed divided by the frequency.

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

millimeters per microsecond (mm/μs) Propagation speed can be measured in millimeters per microsecond.

What is pressure measured in?

pascals or pounds per square inch Pressure is measured in pascals or pounds per square inch.