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104 Cards in this Set

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Heating depends most directly on

SPTA

The time average intensity refers to intensity average of

Pulse repetition period

The following signals represent intensities from a pulse echo scanner. which valve is the highest?

I(SPPA)

Which intensity has the lowest value

I TA (on and off)

The term I m defines the

Maximum intensity and has units of watts per centimeter squared

The SPTP intensity of a typical post acoustic wave

Exceeds The SATA intensity, exceeds the SPTE intensity, exceeds the SATP intensity (all of them)

If an unfocused transducer produces 10 MW of power and the transducer has an area of 2 cm² the SATA at the transducer surface is

5 mW/cm^2

The AIUM statement on bioEffects claims that there have been no KNOWN effects from exposure to tissue at spatial peak temporal average intensities below for a focused sound beam

1000 mW/cm^2 (1W/cm^2)

The AIUM statement on bio affects claims that there have been no known affects from exposure to tissue at spatial peak temporal average intensities below for an unfocused sound beam

100 mW/cm^2

Another term for beam uniformity ratio is

SP/SA factor

All of the following are unitless except

Frequency

The (SA) spatial average for the ultrasound beam is 30. The SP (spatial peak) intensity is 60. The BUR ratio is (SP/SA)

60/30

A sound beam with equal intensities across the beam will have a beam uniformity ratio that is equal to

One

Ultrasound transducer A has a uniformity factor of five. Transducer B has a beam uniformity ratio of one. Which transducer has the brighter center

Transducer A

If BUR is greater than one the center of the beam has higher BUR values

Two acoustic beams have identical SPTP intensities of 400 MW/cm². One beam is pulse while the other is continuous wave. Which beam has the highest SPTA intensity

The continuous wave

What are the acceptable units for the beam uniformity coefficient

None of the above

It’s always unitless

What is another name for the beam uniformity coefficient

SP/SA factor

Acoustical power is given in

Watts

Units for acoustical intensity are

Megawatts per centimeter squared

Which of the following devices are used for measuring acoustical pressures and determining acoustical intensities

Hydrophone

Intensity is related to the

Square of the pressure amplitude

The following signals represent intensities from a pulse echo scanner. Which value is the highest

I(SPPA)

The ultrasound mode producing the highest spatial peak time average intensity is

Pulse Doppler

Which intensity has the lowest value

TA(includes on and off)

The AIUM statement on bioEffects claims that there have been no known effects from exposure to tissue at spatial peak temporal intensity below _______ in and unfocused beach

100 mW/cm^2

Heating depends most directly on

SPTA

The time average intensity refers to intensity average of

Pulse repetition period (on & off)

If an unfocused transducer produces a power of 20 MW of power, and the transducer has an area of 2 cm², the I(SATA) transducer surface is

10 mW/cm^2

P/A 20/2=10

The AIUM statement on bioeffects claims that there have been no known effects from exposure to tissue at spatial peak temporal intensity is below _______ in and focused beam

1000 mW/cm^2

All of the following are accepted for ultrasound bioeffects except

Transducer type

______________ cabbie ocean is the expansion and contraction of gas bubbles with potential micro streaming

Stable

The AIUM has stated that there has been no confirmed reports of adverse affects to living mammals if the temperature rise is less than

2°C

All of the following are ways to test for ultrasound effects for ultrasound bioeffects except

Biology

Mechanisms by which ultrasound energy could induce a biological effect include

Heating

At present the best indication that there have been no ill-effects on the human fetus exposed to ultrasound comes from

Epidemiological studies

Exposure of cells in a fluid is an example of

In vitro study

To minimize exposures to ultrasound, sonographers should scan using

Low transmit power, high receiver gain

___________________ is the science of identifying and measuring the characteristics of an ultrasound beam that are relevant to its potential for producing biological effects

Dosimetry

Protocol is established in specific information is obtained

Prospective study

When testing ultrasound equipment for cyst detection the best method is

Tissue equivalent test object

What standard is best used in a quality assurance program

Objective

What form of resolution is evaluated by measuring the width of reflections arising from small point targets

Lateral resolution

What form of resolution is evaluated by visualizing closely spaced pins that are parallel to the beams main access

Axial resolution

At what intervals should quality assurance evaluations be performed

Routinely

What potential bioeffect occurs through absorption of sound energy by tissue

Heating

Thermally induced biologic affects should be preventable by avoiding a local tissue temperature increase exceeding

1°C

Which intensity descriptor has the lowest numerical value for the characterization of a pulsed wave ultrasonic field

SATA

Increased tissue heating could occur when you

Increase transmit power

A study designed to determine if there is an association between an adverse effect in a population and exposure to a particularly agent is an

Epidemiologic studies

What does the mechanical index indicate on an ultrasound system

Minutes of exposure time before tissue heating is too great

What should you limit when the thermal index exceeds one

Exposure time

To practice the ALARA principle which of the following techniques should you employ

Use the lowest transmit power that allows the adequate tissue visualization

The thermal index indicates

Minutes of exposure time before heating is too great

Which operator control most likely adjust the intensity of the transmitted pulse

Acoustic output (transmit) power

Of the following would have the highest intensity value

SPTP

Which intensity parameter is not applicable for continuous wave ultrasound

SPPA, SAPA

Which of the following would most likely have the highest SPTA value

PW Doppler

Using a Hydro phone you can measure

Pressure amplitude and duty factor

Which of the following occurs when you use the maximum system gain

None of the above

Per for him being a sonographic examination and noticed that the thermal index is greater than one any increase in temperature would be greatest in

Bone

Which of the following parameters relates to tissue heating

Absorption

The motion of particles and fluid is sometimes observed in an intense ultrasound beam this is termed

Acoustic streaming

You are performing a sonographic examination and noticed that the TI reading is one. What does that indicate

The patient’s temperature has increased 1°C as a result of ultrasound scan

What sonographic application has the lowest FDA approved SPTA value

Ophthalmic

The following advantage is associated with use of the MI and TI indices

Information is available on the screen to help the sonographer implement the ALARA principal

When scanning with PW Doppler you would affect the acoustic exposure by changing which of the following

Pulse repetition frequency

During the performance of an obstetric ultrasound you must adjust your system parameters to improve the image. Which of the parameters would increase acoustic exposure

Increase transmit power

Which of the following statements are true of a tissue equivalent phantom

It has the same propagation speed as that of soft tissue, it attenuates ultrasound at a rate similar to soft tissue, embedded in it are solid masses and cystic structures, it is the device of choice for quality studies

Which of the following is different for a tissue equivalent phantom and an AIUM 100 test object

Grayscale

All of the following may be used to evaluate Doppler systems except

Tissue equivalent phantom

Which modes of Doppler may be assessed with the Doppler phantom

Color flow Doppler, pulse wave Doppler, power mode Doppler, continuous wave Doppler

Which two of the following devices convert ultrasound energy into heat

Hydrophone/Calorimeter

The___________ measures beam intensity at the specific locations, where as a _______________ measures the entire energy and a sound wave

Thermocouple, calorimeter

Which of the following is not a potential mechanism for production of bioeffects from ultrasound exposure to the body

Fractionation

Which of these terms best describes the empirical investigation of bioeffects

Exposure to response time

Comprehensive and scholarly review of bioeffects is performed by the American Institute of ultrasound and medicine for all of the reasons except

Ultrasound is considered highly toxic

True or false: the AIUM considers in ultrasound induced biologic tissue temperature rise of less than 2° Centigrade above normal body temperature is safe for clinical studies

True

In studying bioeffects which research approach is more important

Both mechanistic and empirical

Under which condition is it permissible to perform a diagnostic ultrasound exam

When the benefits outweigh the risks

Some ultrasound of bio effect studies are performed in a vevo what is the meaning of in vivo

Observable in a living body

According to the AIUM at what in situ tissue temperature is there a danger to a fetus

41°C

Which is considered the most important for the sonographer with regards to bioeffects

Duration of the study

Which of the following sound beams has a characteristic that’s most likely to cause temperature elevation in soft tissue

Unfocused

Research has indicated that cavitation____________________

Can be lethal to living things

Which of the following statements regarding cavitation is true

Stable cavitation relates to oscillating bubbles while transient relates to bursting bubbles

Which of the following is related to cavitation bio Effects

MI

Which selection has the highest mechanical index

Low frequency, high pressure

Which sound wave is least likely to Caviation

6 MHz, two megapascals

What is epidemiology The study of

Prevalence of disease

Epidemiologic students of in utero exposure to ultrasound have concluded all of the following findings except

None of the above

Which of the following epidemiologic studies is considered most likely to produce meaningful results

Prospective and randomized

What is the highest SPTA intensity of an on focused ultrasound waves where there has been no observed a bio effects

100 MW/cm²

Certain studies of bio affects are performed in Vitro what is the meaning of in vitro

Discernible in a test tube

Which component of an ultrasound system exposes a patient’s greatest risk

Transducer

Two acoustic beams have identical SPTP intensities of 400 MW/cm². One beam is pulsed while the other is continuous wave. Which beam has the highest SPTA intensity

Continuous wave

The term I sub M defines ________the and has units of____________

Maximum intensity, watts per centimeter squared

With a continuous wave sound of being which of the following four intensities are the same

SAPA & SATA

The SPTP intensity of a typical pulsed acoustic wave

Exceeds the SATA intensity exceeds the PSTA exceeds the SATP

What does the beam uniformity coefficient measure

Spatial distribution of sound energy

Which of the following values can correctly designate both the duty factor in the beam uniformity coefficient

100%

What is the importance of describing sound beam intensity is in a variety of ways with regard to space and time

It’s important when studying bio effects

True or false: one reason focused ultrasound beams with low intensity’s are less likely to cause bioeffects is it a focused beam is less efficient and heating a large mass of tissue to a critical temperature

True

True or false: focused sound beams are considered less likely to create bioeffects because the beams will strike fewer gas bubbles that could potentially caviate

True

True or false: is generally believed that the ultrasound bioeffects are minimal at intensity levels of those produced by diagnostic imaging appointment

True