Bioeffects

Question 1

Which two of the following devices convert ultrasound energy into heat?

a. a calorimeter
b. a thermocouple
c. a hydrophone
d. a Schlieren

Answer 1

a. a calorimeter

b. a thermocouple

Question 2

The _____ measures beam intensity at specific locations, whereas a ______ measures the entire energy in a sound beam.

a. calorimeter, thermocouple
b. Schlieren, thermocouple
c. thermocouple, calorimeter
d. thermometer, hydrometer

Answer 2

c. thermocouple, calorimeter

Question 3

True or False?

The biological effects of ultrasound are thought to be negligible and thus, few investigations have been performed on the subject.

Answer 3

False

Question 4

True or False?

It is generally believed that the effects of ultrasound on biologic media are minimal.

Answer 4

False

Question 5

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

a. when the patient will benefit
b. when the patient has insurance
c. when the exam is perfectly safe
d. when the benefits outweigh the risks

Answer 5

d. when the benefits outweigh the risks

Question 6

Some ultrasonic bioeffects studies are performed in vivo. what is the meaning of the term in vivo?

a. observable in a living body
b. observations based on an experiment
c. discernible in a test tube
d. estimated in a computer simulation

Answer 6

a. observable in a living body

Question 7

Certain studies of bioeffects are performed in vitro. What is the meaning of in vitro?

a. visible in a living organism
b. observations based on experiments
c. discernible in a test tube
d. perceptible in a living human being

Answer 7

c. discernible in a test tube

Question 8

Which component of an ultrasound system exposes a patient to greatest risk?

a. the CRT
b. the electric cord
c. the pulser
d. the transducer

Answer 8

d. the transducer

Question 9

True or False?

The AIUM suggests that in vitro research confirming bioeffects is valuable and valid. Their results are significant and should be directly applied to the clinical arena.

Answer 9

False

Question 10

True or False?

The mechanistic approach to the study of bioeffects and safety includes the identification of a theoretical construct that could produce an effect.

Answer 10

True

Question 11

True or False?

The empirical approach to the study of bioeffects and ultrasonic safety surveys data involves finding a relationship between exposure and toxic effects.

Answer 11

True

Question 12

True or False?

A bioeffect identified through the mechanistic approach rather than the empirical approach is more likely to have clinical significance.

Answer 12

False

Question 13

True or False?

The AIUM considers an ultrasound-induced biologic tissue temperature rise of less than 2 degrees Centigrade above normal body temperature as safe for clinical studies.

Answer 13

True

Question 14

Which of the following terms best describes the mechanistic investigation of bioeffects?

a. cause-effect
b. exposure-response
c. cause-response
d. exposure-cure

Answer 14

a. cause-effect

Question 15

Which of these terms best describes the empirical investigation of bioeffects?

a. cause-effect
b. exposure-response
c. cause-response
d. exposure-cure

Answer 15

b. exposure-response

Question 16

When studying bioeffects, which research approach is more important?

a. empirical
b. mechanistic
c. neither is important
d. both are equally important

Answer 16

d. both are equally important

Question 17

Of the following choices, which is considered the most important for the sonographer with regard to bioeffects?

a. pulse repetition frequency
b. frequency
c. duration of the study
d. imaging mode

Answer 17

c. duration of the study

Question 18

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

a. temperature elevation
b. fractionation
c. cavitation
d. vibration

Answer 18

b. fractionation

Question 19

Which of the following ultrasound beams has a characteristic that is most likely to cause temperature elevation in tissue?

a. strongly focused
b. medium focused
c. unfocused

Answer 19

c. unfocused

Question 20

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

a. 100 degrees C
b. 98.6 degrees F
c. 1 degree F over normal temperature
d. 41 degrees C

Answer 20

d. 41 degrees C

Question 21

Research has indicated that cavitation _____.

a. never occurs
b. cannot occur with long pulses
c. can be lethal to living things
d. effects are purely theoretical

Answer 21

c. can be lethal to living things

Question 22

Which of the following statements regarding cavitation is true?

a. it has never been observed in any biological media
b. stable cavitation relates to oscillating bubbles while transient relates to bursting bubbles
c. it is a nonlethal bioeffect produced in an animal experiments
d. waves with peak pressures less than 100 MPa can never induce cavitation

Answer 22

b. stable cavitation relates to oscillating bubbles while transient relates to bursting bubbles

Question 23

Which of the following is related to cavitation bioeffects?

a. TIS
b. MI
c. cavitation index
d. pulsatility index

Answer 23

b. MI

Question 24

Which selection has the highest mechanical index?

a. high frequency, high power
b. high PRF, high intensity
c. low frequency, high pressure
d. high spatial pulse length, high PRF

Answer 24

c. low frequency, high pressure

Question 25

Which sound wave is least likely to create cavitation? a. 5 MHz, 2 MPa b. 2 MHz, 4 MPa c. 6 MHz, 2 MPa d. 2 MHz, 2 MPa

Answer 25

c. 6 MHz, 2 MPa

Question 26

What is epidemiology the study of? a. large groups b. the prevalence of disease c. acoustic bioeffects on the fetus d. in vitro effects

Answer 26

b. the prevalence of disease

Question 27

Epidemiologic studies of in utero exposure to ultrasound have included all of the following findings except _____. a. birth weight b. cancer c. structural abnormalities d. none of the above

Answer 27

d. none of the above

Question 28

Which of the following epidemiological studies is considered most likely to produce meaningful results? a. retrospective and prospective b. prospective and randomized c. retrospective and empirical d. prospective and mechanistic

Answer 28

b. prospective and randomized

Question 29

What is the highest SPTA intensity of an unfocused ultrasound wave where there have been no observed bioeffects? a. 1 mW/cm^2 b. 100 mW/cm^2 c. 1000 mW/cm^2 d. 1 W/cm^2

Answer 29

b. 100 mW/cm^2

Question 30

The upper limit for the SPTA of a focused ultrasound wave where there have been no observed bioeffects is ______. a. 1 mW/cm^2 b. 10 mW/cm^2 c. 100 mW/cm^2 d. 1 W/cm^2

Answer 30

d. 1 W/cm^2

Question 31

True or False? One reason focused ultrasound beams with low intensities are less likely to cause bioeffects is that a focused beam is less efficient in heating a large mass of tissue to a critical temperature.

Answer 31

True

Question 32

True or False? Focused sound beams are considered less likely to create bioeffects because the beams will strike fewer gas bubbles that could potentially cavitate.

Answer 32

True

Question 33

True or False? It is generally believed that the ultrasound bioeffects are minimal at intensity levels typical of those produced by diagnostic imaging equipment.

Answer 33

True

Question 34

A comprehensive and scholarly review of bioeffects is performed by the American Institute of Ultrasound in Medicine for all of the following reasons except: a. ultrasound is a versatile technique b. ultrasound has proven widespread clinical utility c. ultrasound is considered highly toxic d. applications of ultrasound are growing considerably

Answer 34

c. ultrasound is considered highly toxic