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Ultrasound Flashcards

(62 cards)

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1
Q

value defining US

A

soundwaaves with frequency greater than .02MHz
(≥ 20k Hz)

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2
Q

what is the piezoelectric effect

A

crystal in the sound head that vibrates when electricity is run through it causing US waves to leave out into the next medium

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3
Q

what does frequency determine

A

depth of US wave penetration

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4
Q

compare 1 MHz to 3 MHz frequencies

A

1 - deeper penetration (>2 to 5cm)

3 - superficial penetration (1-2cm)

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5
Q

explain the depth associated with higher and lower frequency US waves

A

higher - faster vibration, less absorption of US waves

lower - slower vibration, more absorption of US waves

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6
Q

explain the relationship between compression and refraction

A

compression = US waves bringing cells together

refraction = bounce off of each other

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7
Q

explain longitudinal vs transverse wave propagation and tissues associated

A

longitudinal = compression and refraction reaction occurring in soft tissue vertically

transverse = compression and refraction occurring perpendicular to soft tissue

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8
Q

what is the idea of attenuation

A

absorption of US waves will be greatest in the tissue that has a higher collagen content

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9
Q

explain the relationship between US wave intensity and its depth into soft tissue

A

deeper into material = less intense US wave

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10
Q

definition of thermal effect

A

US causing increased tissue temperature

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11
Q

definition of non-thermal effect

A

US wave altering cellular activity

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12
Q

tissues with high attenuation coefficient

A

tendon
ligament
cartilage
scar tissue
joint capsule

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13
Q

tissues with low attenuation coefficient

A

muscle
- anything with high water content

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14
Q

cavitation definition

A

formation of gas-filled bubbles that expand and compress due to US induced pressure changes in tissue fluids

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15
Q

microstreaming definition

A

unidirectional movement of fluids along cell membrane causing cell to rotate

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16
Q

acoustic streaming definition

A

steady, circular flow of cell material caused by US waves

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17
Q

compression definition

A

increased density of material as US waves pass throughr

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18
Q

refraction definition

A

decrease in density of material as US waves pass through

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19
Q

explain flow of material due to microstreaming? why does this happen?

A

very small flow of material due to gas bubbles

–> rotation of cell will change what it comes into contact with

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20
Q

continuous US definition and associated benefit

A

current is delivered continuously to transducer

thermal

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21
Q

pulsed US definition and associated benefit

A

current delivered for limited portion of time to transducer

non thermal

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22
Q

duty cycle definition

A

amount of time current is being delivered

ie = period of time on compared to total pulse period

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23
Q

how does pulsed US percentage differ from ratio

A

% = on time / total time

ratio = on time : off time

ie 1:4 ratio is a 20% pulse
1 on : 5 total

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24
Q

frequency definition

A

number of compression refraction cycles per second

measured in HZ

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25
power definition and unit
amount of energy per unit of time in Watts
26
intensity definition and unit
power/unit of area W / cm²
27
spatial peak intensity
peak intensity of US output over transducer area
28
spatial average intensity
average intensity of US output over the transducer area
29
beam non uniformity ratio
ratio of spatial peak intensity to spatial average intensity
30
what is the value associated with beam non uniformity ratio that is acceptable
5:1 or 6:1
31
what is the effective radiating area
area of the transducer from which the US energy radiates half the size of the transducer energy
32
in a general sense, what is preferred when considering the beam nonuniformity ratio
lower the better
33
ERA associated with US head
5-10 cm² ERA ≈ 1.5 in
34
relationship between ERA and treatment area and effect
if treatment area is 2-3x ERA thermal
35
non-thermal effects of US
increased: skin / cell permeability macrophage responsiveness chemotactic factor and histamine protein synthesis by fibroblasts NO synthesis in endothelial cells proteoglycan synthesis
36
when are non-thermal effects indicated
inflammation phase of healing wound healing blood flow promotion to local area skin permeability for topical meds
37
benefits of thermal US
increased: collagen extensibility joint freedom/ROM blood flow tissue repair decreased: muscle spasms pain
38
how does absorption coefficient relate to temperature changes
higher coefficient = greater temp change lower = less change
39
relation of intensity and frequency for temperature change
less intensity is needed with higher frequencies
40
what is the time associated with optimal US treatment
5-10 min
41
stage of healing associated with intended benefit
acute/inflammatory - non thermal proliferative = non and thermal
42
what is effective for trigger point treatment
US in combination with e-stim
43
what is sonic accelerated US? what is the idea behind it/special considerations
introducing microdamage to chronic disorderly tissue in hopes to stimulate body's natural inflammatory response need MD referral
44
what are coupling agents
medium in which US waves are transmitted through
45
conducting gel vs immersion vs gel pad or water bladder
conducting gel = direct contact immersion = US through water gel pad = US through pad/bladder
46
relationship between coupling agent and absorption
direct contact = most absorption
47
when would immersion or gel/water bladder coupling agent be indicated
highly contoured or uneven surface area of body
48
effectiveness of direct coupling agents
gel > water bladder > immersion
49
temperature increase associated with tissue extensibility
>4° C
50
clinical applications of US
pain reduction heating tendons/ligaments scar tissue/joint contractures soft tissue healing detection of stress fx removal of plantar warts
51
when should pts feel warmth when intending on gaining thermal benefit of US
2-3 minutes
52
what variables would cause duration need to be increased
low intensity low frequency larger ERA thermal effect desired
53
in relation to treated area, what factor of ERA size contraindicates US
>4 x size of ERA
54
dosage related to US
effect should be observed within 1-2 treatments
55
thermal effect dosage suggestion
subacute/chronic stage usually 3x a week
56
non-thermal effect dosage suggestion
acute stage daily
57
explain the timing of US in your overall treatment plan
during / prior to stretching if goal is to increase tissue extensibility via thermal effects not after any treatment that alters sensation
58
how long do the effects of US last
10-15 minutes
59
what is the rate at which the sound head should be moved
4cm / second ie fast enough to preserve motion / slow enough to maintain contact
60
contraindications of US
acute fracture pregnancy (no low back/abdominal) malignancy thrombophlebitis over metal/plastic devices bleeding non-closed growth plates pacemakers
61
thought behind thrombophlebitis contraindication what about implants
could dislodge a clot could heat up molding that holds implant and dislodge it
62
how to document for US
indicate if pulsed or continuous treatment method (if not direct with gel) if medication was included frequency (MHz) intensity (W/cm²) duration pt response

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