Ultrasound Safety

Question 1

bioeffects information from

Answer 1

plant and animal studies, cell studies, epidemiology, interaction mechanisms

Question 2

experiments on plants compared to humans

Answer 2

plant cell structure does not mimic human cell structure

Question 3

how are plant studies useful?

Answer 3

useful for studying effects of cavitation

Question 4

how are animal studies useful?

Answer 4

help determine the conditions under which thermal and nonthermal bioeffects occur

Question 5

the 2 mechanisms of action that can produce biologic effects

Answer 5

thermal and mechanical

Question 6

thermal mechanism of action

Answer 6

attenuation of sound in tissue is primarily caused by absorption or the conversion of sound to heat

Question 7

mechanical mechanism of action

Answer 7

sound/tissue interaction may result in radiation forces, streaming and cavitation

Question 8

ultrasound produces a temperature ____ as it passes through tissue

Answer 8

rise

a rise greater than 1.5 degrees C is considered significant

Question 9

80 known biologic effects are attributed from ____

Answer 9

hyperthermia

including: fetal absorption or abortion, growth restriction, micropthalmia, palatal defects, spinal cord defects

Question 10

temperature increase during diagnostic ultrasound is related to

Answer 10

acoustic source, tissue properties, radiation force, and cavitation

Question 11

stable cavitation

Answer 11

bubbles that oscillate with passing pressure variations caused by streaming liquid that surround suspended cells or intracellular organelles

expand with lower pressures
contract with higher pressures

Question 12

transient cavitation

Answer 12

bubble oscillations are so large that it collapses

results in shock waves, high localized pressures, light emission

Question 13

two indices on the monitor that display output information are

Answer 13

thermal index and mechanical index

Question 14

thermal index

Answer 14

the transducer acoustic output power divided by the estimated power required to raise tissue temperature by 1%
TIS - soft tissue
TIB - bone
TIC - cranial tissue

Question 15

mechanical index

Answer 15

is equal to the peak rarefactional pressure divided by the square root of the center frequency of the pulse bandwidth

Question 16

what thermal index range has no limit?

Answer 16

<0.7

Question 17

which thermal index range is not recommended for use?

Answer 17

> 3.0

Question 18

how could you reduce mechanical index?

Answer 18

setting focal zone further away from the transducer and decreasing ultrasound beam output

Question 19

which mechanical index level is considered not detectable?

Answer 19

< 0.3

Question 20

what mechanical index number should not be exceeded?

Answer 20

1.9

Question 21

what does the ALARA principle stand for?

Answer 21

as low as reasonably achievable

Question 22

spectral doppler have significantly higher output in general from least to greatest

Answer 22

b mode, color doppler = m mode, spectral doppler