Ch. 24 Physics

Question 1

What are the two types of bioeffects

Answer 1

thermal, cavitation

Question 2

Instrument that can measure the acoustic pressure and the sound beams shape

Answer 2

hydrophone AKA microprobe

Question 3

What can a hydrophone measure

Answer 3

period, PRP, PRF, PD

Question 4

Measures force the sound beam creates on any target it comes in contact with

Answer 4

radiation force

Question 5

Based on the interaction of sound and light

Answer 5

acousto-optics

Question 6

A shadowing system called a ______ allows us to view the shape of the sound beam in a medium

Answer 6

schlieren

Question 7

What are the 3 devices that measure the output of the ultrasound transducer by absorption (conversion of sound energy into heat)

Answer 7

calorimeter, thermocouple, liquid crystals

Question 8

Measures the total power in the entire sound beam through the process of absorption

Answer 8

calorimeter

Question 9

Calculates the temp rise related to the power of the sound beam at specific locations

Answer 9

thermocouple

Question 10

Crystals that change color based on their temp

Answer 10

liquid crystals

Question 11

A primary mandate regarding clinical ultrasound is that the benefit to the patient must outweigh the risk of the exam

Answer 11

risk-benefit relationship

Question 12

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

Answer 12

dosimetry

Question 13

Research performed within the living body

Answer 13

in vivo

Question 14

Research performed outside the living body

Answer 14

in vitro

Question 15

2 techniques used to syudy bioeffects

Answer 15

mechanistic approach, empirical approach

Question 16

Begins as a proposal that a specific mechanism has the potential to produce bioeffects (CAUSE AND EFFECT)

Answer 16

mechanistic approach

Question 17

Based on the acquisition and review of information from patients exposed to ultrasound (EXPOSURE AND RESPONSE)

Answer 17

empirical approach

Question 18

Mechanism proposes that bioeffects result from tissue temperature elevation

Answer 18

thermal

Question 19

Predictor of maximum temperature increase under most clinically relevant conditions

Answer 19

thermal index

Question 20

Thermal index is reported in what three ways

Answer 20

TIS, TIB, TIC

Question 21

Soft tissue thermal index

Answer 21

TIS

Question 22

Bone thermal index

Answer 22

TIB

Question 23

Cranial bone thermal index

Answer 23

TIC

Question 24

What absorbs more acoustic energy that soft tissue

Answer 24

bone

Question 25

Maximal heating is related to the beams _____ intensity

Answer 25

SPTA

Question 26

FDA regulator limit is

Answer 26

720W/cm^2

Question 27

Temperature elevation becomes progressively _____ from gray scale imaging to color doppler to spectral doppler

Answer 27

greater

Question 28

Non thermal consists of

Answer 28

radiation force and cavitation

Question 29

Exerted by a sound beam on tissues. Sheer stresses and streaming fluids can distort or disturb biologic structure

Answer 29

radiation force

Question 30

Interaction of sound waves with microscopic, stabilized, gas bubbles (gaseous nuclei) in the tissues

Answer 30

cavitation

Question 31

Occurs at lower mechanical index levels

Answer 31

stable cavitation

Question 32

With stable cavitation, gaseous nuclei tend to

Answer 32

oscillate (expand and contract)

Question 33

May occur at higher MI levels

Answer 33

transient cavitation

Question 34

Transient cavitation is

Answer 34

bubble bursting

Question 35

Transient cavitation produces what highly localized violent effects

Answer 35

colossal temperatures, shock waves

Question 36

Calculated number related to the likelihood of harmful bioeffects from cavitation

Answer 36

mechanical index

Question 37

What two sound wave characteristics is MI related to

Answer 37

peak rarefaction pressure, lower frequency

Question 38

Branch of medicine associated with population studied

Answer 38

epidemiology

Question 39

Best epidemiologic studied are

Answer 39

prospective, randomized

Question 40

Looking forward, protocol is established and specific information is systematically obtained

Answer 40

prospective

Question 41

One group exposed to ultrasound but not the other group

Answer 41

randomized

Question 42

AIUM conclusions

Answer 42

the benefit to the patient outweighs the risk, it is inappropriate to use diagnostic ultrasound in a non medical setting for entertainment