Term 5 Physics

Performing a given experiment in a test tube.

in vitro

Studies determining the frequency and distribution of disease.

epidemiology

Program to provide safety to both the patient and the care giver.

standard precautions

Experiment done in or on living tissue in an artificial environment outside a living organism.

ex vivo

Experimentation done in or on living tissue of a whole living organism.

in vivo

In which of the following emergency situations would CPR or an AED be used?

heart attack or respiratory arrest

All of the following would be an extra precaution if the patient care activities may generate splashed or sprays of blood or body fluid except:

shoe covers

Standard precautions apply to all of the following EXCEPT?

hair

Plant studies are useful for understanding:

cavitational effects on living tissues

Clinical trials are example of which of the following?

in vivo studies

Ultrasound has a small potential to produce a biological effect because:

it is a form of energy

Washing hands before and after an examination are examples of:

standard precautions

The mission of the ALARA principle is to:

reduce the biological effects of ultrasound

Which of the following denotes the likelihood cavitation will occur?

mechanical index

Heating of soft tissue is proportional to the:

operating frequency

Transient cavitation is most dependent on the:

ultrasound pulse

Absorption of the sound beam is highest in:

bone

The use of ultrasound for entertainment is:

discouraged by the medical community

Microbubbles will expand and collapse when:

pressure is applied

Which of the following organizations regulates ultrasound equipment?

FDA

Which of the following intensities is greatest across the sound beam?

spatial peak

When researching the biological effects of diagnostic ultrasound, which intensity is most commonly used?

SPTA

Pulse average is defined as the average intensity:

over the duration of a pulse

With a focused transducer, there are no confirmed significant biological effects in mammalian tissue for exposures below:

1 W/cm²

Which of the following imaging modalities demonstrates the highest intensity?

pulse wave Doppler

Power is defined as:

rate at which work is performed

Pressure changes in soft tissue are most likely to result in:

cavitation

Heat is most dependent on which of the following intensities?

SATA

The use of contrast agents in diagnostic sonography:

may increase the risk of cavitation determin

Which of the following most accurately defines radiation force?

force exerted by the sound beam on an absorber

The common intensity over the extent of a pulse defines:

pulse average

Higher intensities are necessary to produce bioeffects in an:

focused transducer

The American Institute of Ultrasound in Medicine recommends:

prudent use of ultrasound in the clinical environment

Research has revealed transcranial Doppler (TCD) imaging results in:

a rapid increase in the temperature of the cranium

What are the units for power?

mW

Biological studies of the cytoskeleton have shown:

ultrasound-induced changes are temporary

With an unfocused transducer, there are no confirmed significant biological effects in mammalian tissue for exposures below:

100 mW/cm²

Exposure of a fetus to ultrasound is dangerous above:

41 degrees C

Transient cavitation is most dependent on the:

ultrasound pulse

If the stiffness of the medium increases, the propagation speed will:

increase

What is the frequency of a sound wave in soft tissue demonstrating a wavelength of 0.1 mm?

15 MHz

Which of the following is an acoustic variable?

particle motion

The range of frequencies found in a pulse describes which of the following terms?

bandwidth

The time for one pulse to occur defines:

pulse duration

Which of the following units compares the ratio of amplitudes along two points of a sound wave?

dB

Which of the following will most likely decrease the propagation speed of a wave?

increasing the density of a medium

In perpendicular incidence, what percentage of the sound wave will reflect at a boundary if the impedance of medium 1 is 40 rayls and the impedance of medium 2 is 50 rayls?

1%

Attenuation is MOST COMMONLY the result of:

absorption

For short pulses, the quality (Q) factor is equal to:

the number of cycles in the pulse

Which of the following formulas determines the impedance of a medium?

density of the medium multiplied by the propagation speed of the medium

Resistance to the propagation of sound through a medium defines:

acoustic impedance

Overall compensation gain is set at 36 dB. If the gain is reduced by one half, the new gain setting will be:

33 dB

Which of the following occurs when a sound wave strikes a large, smooth surface at a 90 degree angle?

specular reflection

Attenuation of the sound beam is proportional to the:

frequency of the sound wave

Snell’s law determines the amount of:

refraction at an interface

With perpendicular incidence, the larger the impedance difference between the media, the greater the:

reflection

What is the penetration depth of a 3.5 MHz frequency when imaging the abdominal aorta?

1.71 cm

Which of the following is responsible for determining the amount of reflection and transmission of the sound wave?

impedance

At what depth will a 3 MHz frequency demonstrate an attenuation of 9 dB?

6 cm

Attenuation of the sound wave is a result of all of the following EXCEPT:

transmission

Which of the following calculates the duty factor?

pulse duration divided by the pulse repetition period

With perpendicular incidence, what percentage of the incident beam continues to the next medium?

99%

Which of the following are types of cavitation?

transient and stable

Which of the following imaging modalities demonstrates the highest intensity?

pulsed wave Doppler

The study of various factors determining the frequency and distribution of diseases in human community describes:

epidemiology

Which intensity is greatest during the pulse?

temporal peak

The American Institute of Ultrasound in Medicine recommends:

prudent use of ultrasound in the clinical environment

Washing hands before and after an examination are examples of:

standard precautions

What are the units for power?

mW

Which of the following intensities is greatest across the sound beam?

spatial peak

Limiting the exposure time to a fetus is an example of:

ALARA

Heat is most dependent on which of the following intensities?

SATA

Which of the following reduces occupational injuries?

OSHA standards

Which of the following frequencies is within audible range?

15 kHz

Propagation speed through a medium is determined by the:

density and stiffness of the medium

Which of the following is an acoustic variable?

particle motion

If the amplitude of a wave doubles, the intensity will:

quadruple

Regions of low density in a compression wave are termed:

rarefactions

Resistance to the propagation of sound through a medium defines:

acoustic impedance

How long will it take sound to travel 5 cm round-trip in soft tissue

65 us

Attenuation occurring as sound propagates through each centimeter of soft tissue is equal to:

½ operating frequency

Which of the following units measures the attenuation of sound in soft tissue

dB

If the frequency is increased, pulse duration will

decrease

Which of the following will most likely decrease the propagation speed of a wave?

increasing the density of the medium

Bending of a transmitting sound beam once it passes through one medium to another describes:

refraction

Half-value is equal to an intensity reduction of:

3 dB

At what depth will a 3 MHz frequency demonstrate an attenuation of 9 dB?

6 cm

The resonant frequency of a pulse wave is determined by the:

thickness and propagation speed of the element

Heat sterilization is not recommended for diagnostic transducers because:

the piezoelectric properties will be lost

Lateral resolution is determined by the:

beam width

What is the axial resolution in soft tissue when using a 5 MHz frequency with a 2 cycle pulse, and an element thickness of 0.5 mm?

0.3 mm

If the width of the transducer is 5 cm, what is the width at the focal point?

2.5 cm

The near zone length of a 3 mm, 10 MHz transducer is:

15 mm

The distance from the face of a focused transducer to the point of spatial peak intensity is termed the:

focal length

Which of the following best describes apodization?

irregular excitation of the elements in an array to reduce grating lobes

The purpose of backing material in the transducer assembly is to:

reduce the number of cycles in a pulse

Vector array is a type of transducer:

operation

An active element with a thickness of 0.8 mm and a propagation speed of 4 mm/us will have an operating frequency of:

2.5 MHz

Temporal resolution is determined by the:

frame rate

The ability to distinguish two structures in a path perpendicular to the sound beam describes:

azimuthal resolution