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cata 348 > ultrasound > Flashcards

ultrasound Flashcards

1
Q

brief definition of ultrasound

A

Inaudible , acoustic vibrations of high frequency that produce either thermal or non-thermal physiologic effects

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2
Q

ultrasound relies on what

A

Relies on molecular collision for transmission
Collisions cause molecule displacement and a wave of vibration

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3
Q

what is a longitudinal wave

A

Displacement is in the direction of wave propagation
Travels in both liquids and solids (Soft tissue)

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4
Q

do longitudinal wave travel in liquid and in solid

A

yes

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5
Q

what is a transverse wave

A

Displacement is perpendicular to direction of propagation

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6
Q

do transverse wave travels in solid and in liquid

A

no only in solids (bone)

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7
Q

which frequency have greater depth of penetration

A

lower frequencies

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8
Q

which frequency have more superficial absorption

A

higher

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9
Q

vélocity of transmission related to

A

tissue density -> the higher the density the greater the velocity

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10
Q

attenuation is what and du to what

A

Decrease in energy intensity
Decrease is due to absorption, dispersion, or scattering resulting from reflection and refraction

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11
Q

absorption (increase/decrease) as frequency (increase/decrease)

A

increase, increase

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12
Q

which type of tissue decrease absorption

A

tissue high in water content

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13
Q

which type of tissue increase absorption

A

tissue high in protein

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14
Q

where in the body there is the highest absorption rate

A

in bone, nerve, muscle, fat

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15
Q

what determine the amount of reflected or transmitted of ultrasound

A

acoustint impedance (tissue density x speed of transmission )

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16
Q

the most energy will tramitted if the acoustic impedance is

A

the same

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17
Q

the larger the difference in acoustic impedance the (more/less) energy is reflected

A

more

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18
Q

what happen if the transducer is in contact with air

A

completly reflected

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19
Q

transducer through

A

transmitted

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20
Q

muscle/fat interface will do what

A

reflected and refracted

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21
Q

soft tissue/bone interface will

A

reflected, create standing wave or hot spot

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22
Q

step of an ultrasound generator

A

electrical output -> mechanical vibration -> acoustic sound wave-> absorbed in the tissue

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23
Q

role of the crystal in the transducer

A

Crystal converts electrical energy to sound energy through mechanical deformation

When an alternating current is passed through a crystal it will expand and compress

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24
Q

what is the direct effect of the cristal

A

Direct Effect - An electrical voltage is generated when the crystal expands and compresses

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25
Q

what is the indirect effect of the crystal

A

Indirect or Reverse Effect - As alternating current reverses polarity the crystal expands and contracts producing ultrasound

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26
Q

what is the effective radiating area (ERA)

A

That portion of the surface of the transducer that actually produces the sound wave

Should be only slightly smaller than transducer surface

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27
Q

what’s the frequency range of therapeutic ultrasound

A

0.75 to 3.0 MHz

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28
Q

depth of penetration is intensity depend or frequency depend

A

frequency

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29
Q

1 mHZ transmitted or absorpted

A

both, absorbed at 3-5 cm

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30
Q

3 MHz transmit or absorbed

A

absorbed superficialy at 1-2 cm

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31
Q

what is the ultrasound beam

A

concentrate energy in a limited area

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32
Q

larger head of ultrasound beam is more

A

collimated beam

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33
Q

smaller head of ultrasound beam is

A

more divergent beam

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34
Q

how is the distribution of energy near field of ultrasound beam

A

Distribution of energy is nonuniform due to the manner in which waves are generated and differences in acoustic pressure

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35
Q

how are the wave at point of maximum acoustic intensity

A

wave are indistinguishable and arrive simultaneously

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36
Q

how is the distribution of energy far field

A

Energy is more evenly distributed and the beam becomes more divergent

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37
Q

what is the beam non uniformity ration (BNR)

A

Indicates the amount of variability in intensity within the beam

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38
Q

what is the ratio of BNR and what is the ideal BNR and typical BNR

A

Highest intensity found in the beam relative to the average intensity of the transducer

ideal: 1:!
typical: 6:1

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39
Q

The (lower/greater) the BNR the more even the intensity

A

lower

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40
Q

better generator have (lower/greater) BNR and why

A

low because provide more even intensity through the field

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41
Q

if the intensity is 1.5 W/cm2 the peak intensity in the field would be

A

9 W/cm2

42
Q

what is the PAMBNR

A

represent the size of the peak intensity

43
Q

what does a small PAMBNR represent

A

small or any hot spot

44
Q

large PAMBNR means what

A

large hot spot

45
Q

pulsed ultrasound vs continuous ultrasound

A

continuous: intensity remains constant over time
pulsed: intensity is interrupted thys averege intensity of output over time is low

46
Q

duty cycle may be set to _% or _ %

A

20 or 50

47
Q

intensity means

A

rate at which energy is delivered per unit area

48
Q

recommandation for intensity

A

lowest intensity at the highest frequency which transmits energy to a specific tissue to achieve a desired therapeutic effect

49
Q

thermal vs non-thermal effects

A

thermal: tissue healing
non-thermal ; tissue repaire at the cellular level

50
Q

when does thermal effect occurs

A

whenever the spatial average intensity is > 0.2 W/cm2

51
Q

t/f Whenever there is a thermal effect there will always be a non-thermal effect

A

t

52
Q

when do we want to use thermal effect

A

Increased collagen extensibility
Increased blood flow
Decreased pain
Reduction of muscle spasm
Decreased Joint stiffness
Reduction of chronic inflammation

53
Q

what is mild, moderate, vigorous heating

A

mild: increase of 1º
moderate: increase of 2-3º
vigorous: increase of 3-4º

54
Q

effect of mild heating

A

accelerate metabolic rate in tissue, reduce mild inflammation

55
Q

effect of moderate heating

A

reduce muscle spams, pain, chronic inflammation, increase blood flo

56
Q

effect of vigorous heating

A

decrease viscoelastic propreties of collagen, increase ROM and tissue extensibility

57
Q

effect of non-thermal

A

Increased fibroblastic activity
Increased protein synthesis
Tissue regeneration
Reduction of edema
Bone healing
Pain modulation

58
Q

all of non-thermal physiologic effect occurs through what

A

acoustic micro streaming and/or cavitation

59
Q

what is micro streaming

A

Unidirectional flow of fluid and tissue components along the cell membrane interface resulting in mechanical pressure waves in an ultrasonic field

60
Q

what miscrostreaming do the cell membrane

A

alter permeability to sodium and calcium

61
Q

what is cavitation

A

Formation of gas filled bubbles that expand and compress due to pressure changes in fluid

62
Q

stable cavitation result in

A

in an increased fluid flow around these bubbles

63
Q

what is unstable cavitation

A

results in violent large excursions in bubble volume with collapse creating increased pressure and temperatures that can cause tissue damage

64
Q

therapeutic benefits are derived only from stable or unstable cavitation ?

A

stable

65
Q

how can we maximized non-thermal effect

A

while minimizing thermal effect : using spatial average intensity of 0.1-0.2 W/cm2 with continuous ultrasound, set duty cycle at 20% at 1 W/cm2 or set duty cycle at 50% at 04 W/cm2

66
Q

which conditions btw acute or chronic require more treatment over a short period of time

A

acute 2x/day for 6-8 days

67
Q

which condition btw acute and chronic require less treatment over a longer period

A

chronic alternating day for 10-12 treatments

68
Q

what is the limit treatment for ultrasound

A

14

69
Q

consideration for determining treatment duration

A

size of the area to be treated
what we want to do btw thermal or non-thermal effect
intensity of treatment

70
Q

size of treatment area should be 2-3 time (larger/smaller) Thant the _ of the crystal transducer

A

larger, ERA

71
Q

what needed to be done if the area to be treated is larger

A

use shortwave diathermy, superficial hot pack or hot whirlpool

72
Q

increase intramuscular temperature at 3cm after 10 min with hydrocollator pack and 1 MHz ultrasound

A

hydro: 0.8 º
mhz: 4.0º

73
Q

increase temperature at 1cm below fat layer after 4min with hot whirlpool and 3 MHz ultrasound

A

hot: 1.1
mhz: 4.0

74
Q

ultrasound intensity should be adjusted considerate what

A

patient tolerance,Increase to the point where there is warmth and then back down until there is general heating

75
Q

what to do if you decrease intensity during treatment

A

increase treatment duration

76
Q

ultrasound should be ( temperature/ time) dependant not (temperature/time) dependant

A

temperature, time

77
Q

purpose of coupling method

A

minimize air and maximize contact with the tissue

78
Q

name some coupling method and the best one

A

Include gel, water, mineral oil, distilled water, glycerin, analgesic creams
Gel seems to be the best coupling medium

79
Q

name some coupling method and the best one

A

Include gel, water, mineral oil, distilled water, glycerin, analgesic creams
Gel seems to be the best coupling medium

80
Q

benefit of heating gel

A

patient confort but don’t increase efficiency of treatment

81
Q

benefit of immersion technique

A

good for treating irregular surface

82
Q

what should be use for the immersion technique

A

A plastic, ceramic, or rubber basin should be used
Tap water is useful as a coupling medium

83
Q

transducer should move how with the surface at _ cm

A

parallel at 0.3-0.5 cm

84
Q

bladder technique is good for

A

treating irregular surface

85
Q

what is use with bladder technique

A

balloon filled with water, both side of balloon should be liberally coated with gel

86
Q

applicator should be moved at about

A

4 cm/sec

87
Q

is stationary technique recommend

A

no

88
Q

low bnr allow for slower or rapid movement

A

slower

89
Q

what can arrive with high bar

A

cavitation and periosteal irritation

90
Q

do cooling the tissue does facilitate an increase in temperature

A

no

91
Q

analgesic effect of ice can interfere with what

A

perception of heating

92
Q

what can be use to treat myofascial trigger point

A

ultrasound and EMS when used in combination with stretching

93
Q

ultrasound is recognized as a effective modality to treat what

A

soft tissu and boney lession

94
Q

what happen physiologically when using ultrasound soft tissue healing and repair

A

During inflammatory stage cavitation and streaming increases transport of calcium across cell membrane releasing histamine
Histamine stimulate leukocytes to “clean up”
Stimulates fibroblasts to produce collagen

95
Q

how does ultrasound help with scar tissu and joint contracture

A

Increased temperature causes an increase in elasticity and a decrease in viscocity of collagen fibers
Increases mobility in mature scar

96
Q

ultrasound is seams effective with chronic inflammation because

A

Ultrasound does seem to be effective for increasing blood flow for healing and reduction of pain

97
Q

benefit of ultrasound with bone healing

A

Ultrasound accelerates fracture repair
Ultrasound given to an unstable fracture during cartilage formation may cause cartilage proliferation and delay union (Dyson, 1989)
Ultrasound has no effect on myositis ossificans but may help reduce surrounding inflammation
Ultrasound not effective in detecting stress fractures

98
Q

do ultrasound help decrease pain

A

no but may increase threshold for activation of free nerve ending, superficial activation of free nerve ending and may affect gating

99
Q

t/f ultrasound help drive topical application into tissue

A

t

100
Q

why using ultrasound help to drive topical application

A

non-thermal effect increase tissue permeability and acoustic pressure drive molecule into tissue

101
Q

reasons for hot spot

A

not moving enough
ERA/BNR
close to bone

cata 348 (7 decks)

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