US

Question 1

What is ultrasound

Answer 1

deep heater for small area

Question 2

what is piezoelectricity?

Answer 2

materials generating electrical potential in response to mechanical stress

Question 3

what is direct piezoelectric effect

Answer 3

production of electricity when stress applied

Question 4

what is converse piezoelectric effect

Answer 4

production of stress and/or strain when electric field applied

Question 5

what do transducers do

Answer 5

exploit piezoelectric effect

cause crystals to vibrate –> generate pulses by compressions and refractions

Question 6

4 phenomena when pulses pass through tissue

Answer 6

absorption, reflection, refraction, attenuation

Question 7

what is absorption

Answer 7

conversion of mechanical energy into heat

Question 8

what is reflection? where does it occur?

Answer 8

return of energy; moves in opp direction

occurs at tissue interfaces

Question 9

what is refraction?

Answer 9

redirection of energy at interface

Question 10

what is attenuation

Answer 10

loss of energy as it travels through tissue

absorption and scattering, by reflection and refraction

Question 11

when is attenuation higher

Answer 11

in tissue with higher collagen content

Question 12

what tissue responds best to US

Answer 12

high collagen content: lig, tendon, jt capsules, fascia

Question 13

what structure is at risk for overheating

Answer 13

fat

Question 14

why is US not ideal for heating mus

Answer 14

-low absorption
-they’re too big and deep

Question 15

what is the half value depth for 3MHz

Answer 15

2.5 cm

Question 16

what is the half value depth for 1MHz

Answer 16

4.0cm

Question 17

define power. units?

Answer 17

amount of acoustic energy per unit time (watts)

Question 18

define intensity

Answer 18

amount of power per unit area (W/cm2)

Question 19

define frequency. units?

Answer 19

cycles per unit time

Hz, cycles per sec

Question 20

what is effective radiating area (ERA)?

Answer 20

area of crystal from which US waves radiate

Question 21

what is beam nonuniformity ratio (BNR)? what is clinically appropriate?

Answer 21

ratio of set intensity to max peak intensity

2:1 or 3:1

Question 22

what is duty cycle

Answer 22

ratio of on time to total cycle time

Question 23

3 non-thermal effects

Answer 23

acoustic streaming, micro streaming, and cavitation

Question 24

what is cavitation

Answer 24

sonically generated act of gas and/or vapor filled bubbles

Question 25

what is acoustic streaming

Answer 25

steady circular flow of cellular fluids

Question 26

what is microstreaming? what does it affect?

Answer 26

smaller version of streaming affects cells directly, causes cell lysis

Question 27

5 effects of non-thermal effects

Answer 27

-increase cell membrane permeability and cell diffusion -increase intracellular Ca2+ -increase protein synthesis -fibroblast stimulation -affects macrophage responsiveness

Question 28

what is the effective temp range for thermal effects? minimum time?

Answer 28

40-45 degrees C for at least 5 mins

Question 29

what causes faster heating

Answer 29

increased intensity and frequency

Question 30

what causes faster heating d/t absorption

Answer 30

higher protein tissue

Question 31

5 thermal effects

Answer 31

-increase metabolic rate and enzymatic act -vasodilation -increase collagen extensibility (ROM) -decrease sensitivity to neutral elements (decrease mus spasm) -alter nerve conduction --> increase circulation

Question 32

how deep can 1MHz and 3MHz penetrate

Answer 32

up to 5 cm up to 1-2 cm

Question 33

9 indications for US

Answer 33

-soft tissue shortening -pain -dermal ulcers -surgical skin incisions -tendon injuries -resorption of Ca deposits -bone fx -carpal tunnel -phonopheresis

Question 34

dermal ulcer: thermal or non-thermal effect?

Answer 34

non-thermal acoustic streaming and cavitation

Question 35

clinical implications for dermal ulcers

Answer 35

-pulsed at low doses may accelerate healing for chronic wounds -3MHz -infected more effective

Question 36

clinical implications for tendon injury (settings)

Answer 36

0.5-1 W/cm2 may have faster recovery

Question 37

mechanism for bone fx? clinical implications

Answer 37

piezoelectric effect --> osteogenic (new bone formation; non-thermal) low dose may reduce fx healing time esp in first 2 wks

Question 38

mechanism for phonophoresis

Answer 38

alters skin permeability (stratum corneum), thermal or nonthermal

Question 39

clinical implications for phonophoresis

Answer 39

high frequency, pulsed for max effect on skin permeability and drug penetration

Question 40

2 contraindications/precautions for corticosteroid

Answer 40

nursing or pregnant

Question 41

SE of corticosteroids/phono.

Answer 41

-thin skin -poor healing -vessel fragility -acne -alopecia -oral thrush -glaucoma -ulcers -osteoporosis

Question 42

how big is the tx site

Answer 42

2-4x ERA

Question 43

pad (bladder) method

Answer 43

mass of conductive gel conforms to tx area

Question 44

what is the immersion technique

Answer 44

-used to tx oddly shaped areas -limb in degassed H2O -transducer 1" from body part -avoid making bubbles

Question 45

describe the wand motions

Answer 45

overlapping circles overlapping parallel strokes in both movements overlap no more than 1/2 ERA

Question 46

what percentage doesn't have thermal affect

Answer 46

20%