VCU DPT - Agents (Ultrasound PART 1)

what is ultrasound

high frequency mechanical waves delivered using acoustic energy

which has higher density, compression or rarefactions

compressions

_______ are areas of increased density

________ are areas of decreased density

compression

rarefaction

more dense a tissue is, the ________ effecient it is in transmitting energy

more

compression + rarefaction = ?

1 ultrasound wave cycle

t/f: all forms of sound consist of waves that transmit energy by alternating compression + rarefaction

true

ultra sound is generated by what

applying a high frequency alternating electrical current to a crystal

compression/concavity of crystal = _______ of material in front of it

expansion/convexity of crystal = ________ of material in front of it

compression

rarification/expansion

when the crystal gets __________, material in front of it expands

when the crystal gets ________, material in front of it compresses

expanded/convexity

compression/concavity

match:

a) when the crystal ___________, material in front of it compresses

b) when the crystal ________, material in front of it expands

1) compresses

2) expansion

3) convexity

4) concavity

a) 1, 4

b) 2, 3

b-mode ultrasound and doppler transducers are ___(diagnostic/nondiagnostic)____, where as non focused and focused are ___(diagnostic/nondiagnostic)___

which do PTs usually use

first two diagnostic

second nondiagnostic

nondiagnostic

what type of non diagnostic transducers do PT use most

non-focused

- thermal, or nonthermal

what is attenuation

energy loss of ultrasound wave as it passes through tissue

what is attentuation caused by (4)

absoportion

refraction

reflection

scattering

________ is when energy is taken up by the tissue it passes through, and account for 1/2 of ultrasound's attenuation

absorption

______ is attenuation with the wave bent from original path, where as ______ occurs on surfaces between tissues of different densities

refraction

reflection

what is scattering in terms of attenutation

occurs w/ irregular surfaces, waves go in all direction

acoustic impedence is detemrined by WHAT

tissue density

ultrasound is best at heating what structures?

why?

can this be good or bad

ligament, tendon, bone

these connective tissues are more dense

can be good bc we target them, but bad in case of bone

more dense CT absorbs ultrasound ______ than less dense tissue

better

what is acoustic impednence

the resistance to molecular motion

ultrasound beam encounters this resistance as it passses through tissue

acoustic enrgy is converted to WHAT

thermal

INFO SLIDE

the four variables we are concerned w/ for ultrasound variables are:

Duration (duty cycle)

Frequency

Intensity

Effective radiating area (ERA)

INFO SLIDE

the four variables we are concerned w/ for ultrasound variables are:

Duration (duty cycle)

Frequency

Intensity

Effective radiating area (ERA)

________ is the proportion of total treatment that the ultrasound is on

100% means WHAT

- what effects does it have

20% means WHAT

- what effects does it have

duty cycle

continous

thermal

pulsed

nonthermal

100% duty cycle has __(thermal/non thermal)__ effects, leading to (a/b)

20% duty cycle has __(thermal.non thermal)__ effects, leading to (a/b)

a) therapuetic heating effects

b) promotion of tissue repair

100%: thermal, a

20%: non thermal, b

which is THERMAL

cotinous

pulsed

continous

which is NON THERMAL

continous

pulsed

pulsed

_______ is the number of compression-rarefaction cycles per unit of time

frequency

the higher the frequency, the __(deeper/shallower)__ the ultrasound goes

shallower

increased frequency decreases depth of penetration

increased frequency leads to ____________ depth of penetration

increased frequency leads to _______ rate of tissue heating

normal range of frequency?

decreased

increased

1 to 3 MHz

3 MHz:

- higher concentration of US energy, provides _______ penetration

goes _____ inches deep

best for _______ tissue

heats tissue ______ than low frequency

shallower

1

superficial (ex exposed tendon, lig)

faster

1 MHz:

- lower concentration of US energy, provides ____ penetration

goes ___ inches deep

best for ______ tissue

deeper

2

deeper (muscle, fascia)

intensity is in what units

watts/cm^2

________ is the rate at which ultrasound energy is deleviered

ALSO

______ = Power/effective radiating area

intensity

the higher the intensity is for ultrasound, the __(more/less)__ comfort the patient will have

less

what is beam nonuniformity ratio (BNR)

the crystal in ultrasound is not a uniform shape, and will contract/expand non uniformily; variations exist in its beam

ratio between peak intensity and average intesnity

ratio between peak inteisty and average intensity in a US beam is ______

beam nonunfirmoty ratio

lower BNR means _____________

impact on hotspots?

cost?

acceptable BNR range

the beam is more uniform

less hot sports

more expensive

2-6

with BNR, we can improve patient comfort by (3)

using unit w/ lower BNR

cotinously moving the US head to avoid hotspot in one area

decreasing intensity

the area of ultrasound should be no bigger than ____________

2x the size of effective radiating are a(ERA)

what is effective radiating area

area of transducer that the US energy radiates off of

which is ultrasound better for, small areas or big areas

small

should be no bigger than 2x the ERA

which is more important, ERA or speed of application

ERA

with thermal ultrasound:

is it continous or pulsed?

to have greater heating, how do we change frequency?

higher density tissues heat ________ and to _____ degree than lower density tissue

continous (100% duty cycle)

increase it

faster, greater

should patient feel warmth if thermal ultrasound is the goal

YES

with thermal ultrasound, the inteisty should be 3-4x _______ when applying 3 MHz compared to 1 MHz

lower

when trying to increase tissue mobility, we need to heat it _____ deg F

7-7.2

if continous is goal, patient should/should not feel warmth

if pulsed is goal, patient should/should not feel warmth

should

should not

to heat tissue ______ deg C, we use:

0.6 1W/cm^2 4 min

2.4

to get increased tissue extensibility with stretching from ultrasound heating, it needs to be at ____ deg F

how long generally do we have to see results

7

very quickly, almost immediatly to within a minute or two

with ________ ultrasound, the theroy is movement of fluid changes cell memrbane permeability from acoustic streaming and caviation

- what is the end result

pulsed/nonthermal

stimulates responses needed for tissue healing

clinical indications for...

a) thermal ultrasound

b) nonthermal ultrasound

c) both

a) soft tissue shortened, pain reduction

b) help tissue heal, ulcers, fractures

c) tendon injuries (also maybe phonoporesis)

is the evidence good for ultrasound for

acute ankle sprain

OA

LBP

myofascial pain

shoulder conditions

lateral epicondylitis

bursitis

NO

- maybe with LBP

is evidence good for ultrasound for:

carpal tunnel syndrome

arthritis

tissue extensibility

maybe soft tissue healing

they are all okay

arthritis for pain

tissue extensibility with the catch you should static stretch last 1-2 min of treatment

soft tissue healing HARD MAYBE

what are the two best use cases for ultrasound, using support from literature

chronic wounds

tissue extensiblity

to get benefits from ultrasound for tissue extensibility, what does the literature say you need to do

hold a static stretch for last 1-2 min of treatment