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