Exam 1.1

What is the wavelength of 5 MHz ultrasound in soft tissue?

0.3 m

The duty factor for continuous wave ultrasound is

100%

If the period is 0.5 us (microseconds), what is the frequency?

2 MHz

The typical range of frequency for diagnostic ultrasound imaging is

2- MHz- 15 MHz

In clinical imaging a pulse typically contains ____ cycles

2-4

What is the frequency of a sound wave with 16 cycles in 4 seconds?

4 Hz

4 MHz is ______ Hz

4,000,000

If the wavelength is 2 mm, the spatial pulse length for a three cycle pulse is ____ mm

6

An increase in pulse repetition frequency would lead to

An increase in duty factor

Increasing the frequency on a multifrequency transducer from 3.5 MHz to 5.0 MHz will:

Decrease Wavelength

Density is typically measured in

Kilograms per centimeter cubed

Spatial pulse length can be calculated by

Multiplying the number of cycles times the wavelength

Which of the following is an appropriate unit of measurement for propagation speed? a. millimeters per microsecond (mm/us) b. watts per centimeter squared (w/cm) c. microseconds (us) d. kilohertz (kHz)

a. millimeters per microsecond (mm/us)

Which of the following would have the highest propagation speed? a. air b. bone c. soft tissue d. water

b. bone

Which of the following is considered the speed of sound in soft tissue? a. 1.54 m/s b. 330 m/s c. 4000 m/s d. 1.54 mm/us

d. 1.54 mm/us

Which of the following frequencies has the longest period? a. 2 MHz b. 4000 Hz c. 1 KHz d. 6 Hz

d. 6 Hz

Which intensity is most relevant with respect to bioeffects? a. SATA b. SPTP c. SPPA d. SPTA

d. SPTA

A sonographer increases the amplitude of a sound wave by a factor of 4. How has the power change?

increases by 16- fold

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

Sound is a ______ wave where particles move in the same direction that the wave propagates

longitudinal

Sound is technically a

mechanical and longitudinal wave

Micro denotes

millionth

The prefix "micro" denotes

millionth

Which of the following is described as the distance over which one cycle occurs? a. pulse duration b. duty factor c. period d. wavelength

wavelength

If the frequency is 1 MHz, what is the period?

1 us

Select the sequence of the following prefixed of metric system that appears in decreasing order: a. M, G, da, m, k b. G, M, k, da, d c. G, n, M, k, da d. M, G, m, h, k

b. G, M, k, da, d

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 c. it is inversely related to frequency d. it is directly related to period

b. it is equal to the period divided by the frequency

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 c. increasing stiffness increased propagation speed d. stiffness is the opposite of elasticity and compressibility

b. stiffness and propagation speed are indirectly associated

All of the following relate to the strength of the sound wave except: a. amplitude b. wavelength c. intensity d. power

b. wavelength

Which of the following would be considered ultrasonic? a. 10 Hz b. 12.5 kHz c. 1 MHz d. 20,000 Hz

c. 1 MHz

Which of the following intensities has the highest value? a. SATA b. SPTA c. SPTP d. SPPA

c. SPTP

if the frequency is unchanged but the propagation velocity changes, the wavelength

changes

Areas of high pressure and density are referred to as:

compressions

Which of the following characteristics will create the slowest speed of sound? a. high density, high stiffness b. low density, high stiffness c. low density, low stiffness d. high density, low stiffness

d. high density, low stiffness

All of the following characteristics create pulses of short duration except: a. short pulse duration b. few cycles in the pulse c. individual cycles with short periods d. many cycles in the pulse

d. many cycles in the pulse

Which of the following is defined as only the active time a. duty factor b. pulse repetition frequency c. period d. pulse duration

d. pulse duration

As imaging depth increases the pulse repetition frequency must:

decrease

The speed of sound

depends on density and elasticity of medium

Duty factor can be calculated by

dividing pulse duration by pulse repetition period

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

duty factor

T/F. Log pulses create more accurate images

false

The prefix "centi" denotes

hundredths

As imaging depth increases, pulse repetition period

increases

Pressure is typically expressed in

pascals

If only the density of a medium is increased then the

propagation speed will decrease

What is defined as the beginning of one pulse to the beginning of the next pulse?

pulse repetition period