Ch 7 Performance & Safety

Question 1

No confirmed adverse effect in mammals exposed in vivo:

Answer 1

Below 1 W/cm2 SPTA
W/ low megahertz range
And
Focused beam

Question 2

Typical output intensity (SPTA) for US

Answer 2

1 mW/cm2

Question 3

Hydrophone membrane made of

Answer 3

Polyvinylidene fluoride (PVDF)

Question 4

Temp rises significant if

Answer 4

Exceed 2 degrees C

Question 5

Tissue phantoms simulate tissue properties and assess:

Answer 5

Detail/contrast resolution, penetration, dynamic range, and TGC

Question 6

Tissues w/ well-defined gas (like lungs) have been observed for in situ peak rare factional pressures

Answer 6

Below 0.4 MPa or MI less than 0.4

Question 7

Highest acoustic pressure output

Answer 7

Spectral Doppler

Question 8

Lowest outputs

Answer 8

Gray-scale

Question 9

Attenuation due to

Answer 9

Absorption (conversion of US to heat)

Question 10

Test objects contain _____ and ______ to evaluate _______ and ________. They do not _______.

Answer 10

Nylon lines; scattering layers
Detail resolution; beam profiles
Simulate tissue characteristics

Question 11

Regular quality control testing required by ___ at a minimum _____.

Answer 11

ACR

Semiannually

Question 12

Bio effects have not occurred below ___. Above that bio effects depend on ___and ___.

Answer 12

39*C

Temp, time

Question 13

Temp increases in tissues close to transducer surface significantly caused by

Answer 13

Transducer self-heating

Question 14

Bio effects of hyperthermia:

Answer 14

Fetal absorption/abortion, IUGR, microphthalmia, cataract production, abdominal wall defects, renal agenesis, palatal defects, reduced brain waves, microencephaly, anencephaly, spinal cord defects, renal amyoplasia, forefoot hypoplasia, tibial/fibular deformities, abnormal tooth genesis

Question 15

Phantoms and test objects can be used by

Answer 15

Service personnel and instrument operators.

Question 16

Manufacturers must submit ___ to the ___ before _________.

Answer 16

Pre market notifications
FDA
marketing a device for a specific application in the U.S.

Question 17

No significant adverse bio effects have been observed for exposure duration up to ____ from temp increases ____ above normal.

Answer 17

50 hours

Less than or equal to 2*C

Question 18

Doppler test objects useful for testing:

Answer 18

Effective penetration of Doppler beam
Ability to distinguish different flow directions
Accuracy of sample volume (gate) location
Accuracy of measured flow speed

Question 19

Sonography requires application of _____ principle which requires _______________.

Answer 19

ALARA

medical indication and using minimum output and exposure time necessary

Question 20

Output of some current US machines can generate levels that _____.

Answer 20

Produce hemorrhage in lungs and intestines of lab animals.

Question 21

2007 statement by AIUM:

Answer 21

Required medical indication for diagnostic examinations.

Question 22

Greatest risk from cracked transducer housing:

Answer 22

Electric shock

Question 23

____ regulates outputs

____ evaluates research

Answer 23

FDA

AIUM

Question 24

Freq = 1/?

Answer 24

Period

Question 25

PRF=

Answer 25

1/PRP

Question 26

DF=

Answer 26

PD/PRP

Question 27

Wavelength=

Answer 27

Prop speed/Freq

Question 28

SPL=

Answer 28

#cycles X wavelength

Question 29

MI=

Answer 29

Peak rarefaction pressure (MPA) / | sq root of Freq

Question 30

Types of bioeffect studies

Answer 30

- Experimental observation in cells - Epidemiologic studies on humans - Studies of interaction mechanisms (heating & cavitation)

Question 31

Hydrophone aka Microprobe measures...

Answer 31

Pressure in a sound wave | Calculates Period, PRP, and PD, PRF, DF, freq, pressure amp, wavelength, SPL, intensity

Question 32

Cavitation

Answer 32

Production/behavior of bubbles in liquid.

Question 33

Cavitation types

Answer 33

Stable- oscillates and may cause streaming/stresses Transient- oscillates and collapses; shockwave may cause local extreme high temp and light emission

Question 34

TI Thermal Indices

Answer 34

Real-time display of thermal injury likelihood. Either overestimate or very close TIS- soft tissue TIB- bone TIC- cranial

Question 35

MI Mechanical Index

Answer 35

Likelihood of cavitation effects | No effects confirmed

Question 36

Output Intensities

Answer 36

Highest- Spectral Lowest- Grey scale Color and M mode in between

Question 37

SPTA intensity- Spatial Peak Temporal Average

Answer 37

Most commonly used; | Includes listening time

Question 38

Heat and fetal tissues/bones: Absorption coefficient _______ in bone; Fetal tissue less ____; Most effects in ___ trimester during _____. If temperature is elevated > ____ for ___ min or more it can cause developmental effects.

Answer 38

higher tolerant 1st; organogenesis 4*C; 5

Question 39

In vivo

Answer 39

In living

Question 40

In vitro

Answer 40

In glass

Question 41

Focused beams

Answer 41

less likely to cause temp rise in tissue | Max I= 1,000 mW/cm2 or 1 W/cm2

Question 42

Unfocused beams

Answer 42

more likely to cause temp rise in tissue | Max I= 100 mW/cm2

Question 43

Bioeffect study technique | Mechanistic Approach

Answer 43

Theoretical | Cause and Effect

Question 44

Bioeffect study technique | Empirical Approach

Answer 44

Based on review of info | Relationship btwn exposure and effects

Question 45

Both mechanistic and empirical have merits but...

Answer 45

Strongest argument when both approaches are in agreement

Question 46

Attenuation

Answer 46

Caused by 1)Reflection 2) Scattering 3) Absorption | Increases w/ longer distance and higher frequency

Question 47

Rayleigh Scattering

Answer 47

Scattering that occurs when structure's dimensions are much smaller than the beam's wavelength. Redirects sound equally in all directions. Ex: US and RBCs It increases dramatically w/ increased Freq.: Rayleigh Scatter= Freq^4

Question 48

Contrast Agents

Answer 48

Bioeffects confirmed w/diagnostic US and MI of >0.4 and gas body contrast agent present in circulation.

Question 49

Output Power vs. Receiver Gain

Answer 49

``` Overall brightness- BOTH Alters signal-to-noise ratio- OP Alters patient exposure- OP Bioeffect concerns- OP Decrease OP if image too BRIGHT Increase RG if image too DARK ```

Question 50

Therapeutic US

Answer 50

``` Many uses (chemo, break of calculi, etc.) Long duration US increases blood flow to area and speed healing of MSK injuries ```