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Passive care exam 2 > ultrasound > Flashcards

ultrasound Flashcards

(62 cards)

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1
Q

how does ultrasound work?

A

uses sound waves at high frequencies- acoustical energy

electrical current is passed through a crystal causing it to vibrate

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2
Q

ultrasound is a deep heating modality, what is it traditionally used to treat?

A

muscles, tendons, ligaments, joint capsules scar tissue etc.

penetrates skin and subcutaneous tissue

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3
Q

what is the most common heating modality used by 63% of chiropractors?

A

ultrasound

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4
Q

what is the 2nd most common heating modality in the US?

A

ultrasound

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5
Q

what is the most common heating modality in the US used by 71% of chiropractors?

A

moist hot packs

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6
Q

what is the frequency range for ultrasound machines used for musculoskeletal treatments?

A

0.8 MHz- 3.3 MHz

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7
Q

how are sound waves generated with ultrasound?

A

through the vibration of the crystal- usually quartz, lead zirconate, lead titanate, barium titanate or nickel cobalt

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8
Q

what is calculated by dividing the time sound is delivered by the total treatment time?

A

duty cycle

150ms/1000ms = 15%

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9
Q

what is the duty cycle of continuous ultrasound?

A

100%

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10
Q

which ultrasound type results in tissue heating?

A

continuous ultrasound

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11
Q

which ultrasound type has mechanical and non-thermal effects?

A

pulsed ultrasound

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12
Q

what is the term for mechanical deformation of a crystal causing an electric current to form?

A

piezoelectric effect

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13
Q

what is the term for alternating current passing through a crystal that results in a fast contraction and expansion of the crystal?

A

reverse piezoelectric effect- this vibration produces high frequency sound waves

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14
Q

what is the treatment area or “fresnel zone”?

A

near field

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15
Q

what is the fraunhofer zone?

A

far field

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16
Q

what is the peak intensity or max intensity measured in watts per cm2?

A

spatial peak intensity (Isp)

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17
Q

how is the spatial average intensity (Isa) calculated?

A

Isp x duty cycle

1.4W/cm2 x 50%= 0.7 W/cm2

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18
Q

what does ERA stand for?

A

effective radiating area

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19
Q

what does BNR stand for?

A

beam nonuniformity ratio

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20
Q

what is the area of the sound head that produces sound energy?

A

effective radiating area- always smaller than the ultrasound head but ideally only slightly smaller

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21
Q

what is the amount of variability of a beam used to compare different quality of different machines?

A

beam nonuniformity ratio BNR

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22
Q

what is the ratio between the peak intensity of the beam divided by the average intensity of the beam?

A

BNR

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23
Q

what is the ideal BNR?

A

1:1 but within range of 2:1- 8:1 is acceptable

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24
Q

the lower the BNR the more uniform the intensity of the sound wave, what 3 things does this allow for?

A

eliminates hot spots
allows for higher dosage without discomfort
greatest comfort and safety

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25
what does PAMBNR stand for?
peak area of the maximum beam nonuniformity
26
what describes the area of the sound head covered by peak intensity?
PAMBNR- Peak Area of the Maximum Beam Nonuniformity
27
large PAMBNR means what?
covers a larger area of the sound head and less uniform heating
28
air is a poor conductor of ultrasound, what are 2 things we can do to combat this?
using a coupling medium to prevent reflection of sound waves by air- gel or gel pads keep sound head flat against the skin (90 degrees)
29
underwater ultrasound is direct or indirect?
indirect- using plastic basin or bucket
30
what is the distance needed with underwater ultrasound?
0.5-3 cm
31
what is the amount of sound energy being emitted from the sound head and what is it measured in?
amplitude- measured in Watts
32
more Watts =
more heating NOT greater penetration
33
what is the typical frequency of ultrasound and what does it dictate?
1-3 MHz and it dictates the depth of heating
34
what dictates the depth of heating and time required to cause an increase in tissue temperature?
frequency
35
what is the difference between using high vs low frequency?
high 3MHz= absorbed more rapidly; superficial tissue | low 1MHz= absorbed slower; deeper tissue
36
which frequency is for superficial tissue?
high
37
which frequency is for deep tissue?
low
38
higher protein concentration and higher density = higher or lower absorption rate?
higher
39
what tissue types absorb the most heat?
bone, tendon, ligament, joint and capsule
40
what tissue types absorb the least heat?
skin and fat
41
when US wave encounters a boundary between tissues energy will scatter by?
reflection or refraction
42
what is the reversal of the direction of propagation of the ultrasound wave?
reflection
43
what is the change of ultrasound wave from a straight path when passing obliquely from one medium to another?
refraction
44
US energy is reflected at soft tissue-bone interface leading to _____?
increased heating
45
what leads to the concentration of ultrasound at the point of refraction?
the bending of the ultrasound energy- refraction
46
what degree increase in temperature leads to an increase in metabolic activity?
1 degree
47
what degree increase is associated with reduced muscle spasm, increased blood flow and decrease in chronic inflammation?
2-3 degrees
48
what degree increase alters viscoelastic properties of collagen?
4 degrees
49
though pulsed ultrasound has very little heating of tissues, what are 3 things that it does do for tissue?
stimulation of fibroblast activity increase blood flow increase proteins associated with injury repair
50
how does pulsed ultrasound work to effect tissue?
through acoustical streaming and stable cavitation
51
what is the movement of fluids along cell membranes due to mechanical pressure exerted by sound waves?
acoustical streaming- movement occurs in direction of sound waves facilitates fluid movement and increases cell permeability
52
what is the rhythmic expansion and contraction of bubbles during repeated pressure changes over many acoustic cycles?
stable cavitation
53
what type of cavitation is associated with low frequency high intensity ultrasound and is not therapeutic?
unstable ultrasound
54
what are the contraindications for ultrasound?
``` malignancy hemorrhage ischemia thrombus infection gonads eye pelvic, abdomen, lumbar of pregnant women spinal cord after laminectomy plastic and cemented implants near or over electrical implants unknown etiology ```
55
what is the peak intensity you should not exceed?
8.0 W/cm2
56
what is the range of intensity used?
0.5-2.5 W/cm2
57
what is the approximate treatment are size?
2-3 times the size of the ERA
58
what is the general treatment time parameters?
5-8 minutes; never more than 15 minutes
59
what is the term for using sound energy to drive medication into tissue
phonophoresis/ sonophoresis
60
what are ultrasound and e-stim combos used for?
trigger points epicondylitis superficial pain decrease adhesions
61
what is LIPUS- low intensity pulsed ultrasound used for?
stimulation of fracture healing; home units that can be sent home with patients
62
what is NCLFUS- noncontact low frequency ultrasound used for?
wound cleaning and debridement- US propels saline across wound

Passive care exam 2 (6 decks)

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