UltraSound

Question 1

Production of US

Answer 1

Application of hi-freq ele currect to a piezoelectric transducer creates cycles of compression and rarefaction waves directed at the tissue
Force creates voltage
the crystal transducer converts ele energy INTO mechanical energy (sound waves) (distorts and springs back to NL of the crystal = waves)

Question 2

US Collimates

Answer 2

doesn’t spread out but stays in 1 direct path

if not calibrated correctly can cause some serious damage/burns

Question 3

ERA

Answer 3

Effective radiating area - area of the transducer from which the US energy radiates; just smaller than the head of the US machine
Do NOT treat an area bigger than 2x the ERA

Question 4

Treatment time

Answer 4

8-10 minutes dont want to do for much longer

Question 5

Transmission

Answer 5

Beam 1st converges then diverges
1mHz = depth of 3cm
3mHz = depth of 1-2 cm (superficial and preferred method)

Question 6

Applicator

Answer 6

ALWAYS moving - most E in the middle of the applicator - easy way to burn
ALWAYS flat against the skin!

Question 7

Scattering

Answer 7

reflected and refracted waves

needs a medium (gel) to travel in

Question 8

Absorption

Answer 8

Tissues absorb sound energy
liquids absorb very little sound waves
varies w tissue type (collagen abs lots of E)
tendon> muscle for absorption
dependent upon US frequency

Question 9

Attenuation

Answer 9

decrease in US intensity as it travels thru the tissue
50% is due to absorption
superficial bone if hit will start to have a deep ache

Question 10

Attenuation of 1mHz of various tissues

Answer 10

Mm - 24%
skin - 39%
Tendon - 59%
Cartilage - 68%
Bone* - 96% - bone can get painful quickly w US

Question 11

BNR***

Answer 11

beam nonuniformity ratio
beam is not uniform and therefore center is most intense
depends on the quality of the piesoelectric transducer
BNR = peak intensity/ average intensity
2:1 to 8:1 - want it to be LOW - more even distribution

Question 12

Standing Waves

Answer 12

reflecting surface in exact multiple of the US wavelength - reflects back on the original and doubles the intensity; hence dynamic technique used at 4cm/sec to not produce huge waves

Question 13

Continuous US

Answer 13

greater thermal effects
duty cycle = on time/ total x 100 = 100%
acute injury at 0.5 intensity

Question 14

Pulsed US

Answer 14

appropriate for acute injury bc no heat effecs at 20-50% duty cycle

Question 15

Intensity

Answer 15

rate of E delivered per unit area
W/cm(^squared)
acute = 0.5
subacute = 0.5 - 1.5
chronic = 1.0 - 3.0

Question 16

Ways to control E delivered

Answer 16

Intensity
Treatment duratioln
frequency
duty cycle
area size

Question 17

Thermal Effects

Answer 17

higher dose = more thermal
more collagen = more thermal
~4-5 cm deep
inc tissue extensibility (4 min post)
dec pain/inc pain threshold
promote resorption of Ca deposits
may promote bone healing
inc local BF
inc enzyme activity

Question 18

NonThermal Effects Cavitation

Answer 18

formation of tiny gas bubbles in tissues bc on US vibration - thins membrane bc scrub-brush like
unstable cav = bubbles burst and kills cell

Question 19

Microstreaming

Answer 19

flow of fluid near the vibrating bubbles
“surf” on waves and around membrane to also thin and inc permeability of membrane
allows garbage to get out easier and promote healing

Question 20

Theorized Effects

Answer 20

1. Cavitation and microstreaming may alter membrane permeability and promote soft tissue healing
2. Inc rate of PRO syn
3. Inc intracellular Ca
4. Inc skin permeability –> sonoporation helps phonophoresis

Question 21

Frequency Response Hypothesis

Answer 21

inc Stress = lay down collagen to withstand stress

MECHANICAL stress

Question 22

in vitro

Answer 22

US fires up fibroblasts to inc collagen spewage = stronger tissue

Question 23

Direct Contact

Answer 23

sound head makes direct contact with gel medium

Question 24

Water immersion

Answer 24

treated immersed in water
parallel to skin
plastic container and Not metal

Question 25

Cushion contact

Answer 25

overcoming water with gel pads to US odd shaped body parts

Question 26

Phonophoresis

Answer 26

US to facilitate transdermal delivery of topically applied drug (corticosteroid or NSAID)
treat tissue inflammatory conditions: ..itis
dec inflammation and pain

Question 27

phonophoresis benefits

Answer 27

inc drug concentration at site
prevents gastric irritation
prevents 1st-pass metabolism

Question 28

Phono parameters

Answer 28

US 5 min
US + meds 5 min
gentle wipe away
COVER with occl covering to further diffuse drug
DONT GIVE to pts already receiving drug via another route

Question 29

Power

Answer 29

amount of acoustic energy contained in the beam and delivered per unit of time, expressed in watts
Continuous - P= avg intensity x ERA
Pulsed - P = (avg inten x ERA)/ DC
DC = duty cycle

Question 30

Intensity

Answer 30

acoustic power delivered at the soundhead ERA

Question 31

Contraindications

Answer 31

#1 Cancer - Tumor! if anywhere
hemorrhage
ischemic regions
impaired skin sensation
infected lesions
Pregnancy**
Thrombophlebitis**
Implanted medical device - pacemaker*
chemo
okay over metal

Question 32

Precautions

Answer 32

growth plate in kids
acute inflammation
fractures
breast implants
thermal heating of patellar tendon