Ultrasound & Laser

Question 1

what is ultrasound

Answer 1

• therapeutic modality where high fq sound waves are transmitted through a wand or probe into the body
• sound waves lead to vibrations of the molecules in the body
• waves either reflected, refracted or absorbed

Question 2

what equipment is used with ultrasound

Answer 2

• two main components

- generator and applicator

Question 3

generator for ultrasound

Answer 3

• US device

- generates the high fq alternating current that is transmitted through the applicator

Question 4

applicator for ultrasound

Answer 4

sound head and piezoelectric crystal

Question 5

beam nonuniformity ratio

Answer 5

ratio of spatial peak intensity and spatial avg intensity

Question 6

spatial peak intensity

Answer 6

power of beam at highest point of effective radiating area

Question 7

spatial average intensity

Answer 7

W/cm^2

total power across the transducer head usually what is recorded for intenisty during treatment

Question 8

absorption

Answer 8

when the kinetic energy of movement is absorbed by tissue and transformed into thermal energy

Question 9

refraction

Answer 9

ultrasound signal is deflected from a straight path and the angle of deflection is away from the transducer

Question 10

reflection

Answer 10

ultrasound waves are deflected toward the transducer

Question 11

standing waves

Answer 11

• reflected waves interacting with waves going in and creates more energy
• reduced by keeping sound head moving

Question 12

intensity

Answer 12

power of ultrasonic energy

Question 13

attenuation

Answer 13

reduction of acoustical energy as it passes through soft tissue

Question 14

what affects attenuation

Answer 14

absorption, reflection and refraction

Question 15

when is absorption highest

Answer 15

in tissues of greater density

Question 16

reflection of acoustic waves can create what

Answer 16

standing waves –> increasing intensity

Question 17

frequency

Answer 17

of waves per second delivered

Question 18

3 mHz =

Answer 18

up to 2.5cm deep

greater heat production in superficial layers due to increase in scatter of sound waves in superficial tissues

Question 19

1 mHz

Answer 19

5cm deep

heats deep layers due to less scatter in superficial tissue, more energy able to penetrate deeper

Question 20

duty cycle

Answer 20

mode

fraction of time the US energy is on over one pulse period

Question 21

continuous US

Answer 21

thermal

US is applied at a constant energy level, duty cycle 100%

Question 22

pulsed US

Answer 22

non-thermal

duty cycle range from 5-50%

Question 23

indications for use for US

Answer 23

modulate pain
increase connective tissue extensibility
reduce muscle spasm
increase tissue temp
increase blood flow
facilitate healing

Question 24

contraindications for US (8)

Answer 24

impaired circulation
impaired cognitive fxn
absent sensation
cancer
joint cemet
directly over plastic components
over vital areas
pregnancy

Question 25

precautions (4)

Answer 25

acute inflammation
open epiphyseal plates
healing fx
breat implants

Question 26

proposed impact for thermal US

Answer 26

increase pain threshold
increased collagen extensibility
alteration of nerve conduction velocity
increased enzymatic activity
increased tissue perfusion

Question 27

cavitation

Answer 27

non-thermal
alternating compression and expansion of small gas bubbles in tissue fluids due to the mechanical pressure waves of the acoustic waves

Question 28

stable cavitation

Answer 28

gas bubbles resonate without tissue damage; may be responsible for diffusional changes in cell membrane

Question 29

unstable cavitation

Answer 29

severe collapse of gas bubbles during compression phase of pulsed US which can result in local tissue damage due to high temps

Question 30

acoustic streaming

Answer 30

forward movement of fluid and ions along boundaries of cell membranes

Question 31

when would you use immersion technique

Answer 31

• when criteria for direct contact can’t be safely met

- used on irregular surfaces, sensitive or broken integument

Question 32

what is the immersion technique

Answer 32

• plastic container with water high enough to cover body part
• US head placed 1cm away from treatment area
• perform rhythmical movement over area maintaining perpendicular to treatment area

Question 33

phonophoresis

Answer 33

using US sound waves to attempt to deliver meds through skin

Question 34

if you have an impairment of soft tissue shortening or pain, what US would you use

Answer 34

thermal

Question 35

thermal duty cycle:

Answer 35

100%

Question 36

if thermal/nonthermal US, and depth is 1-2 cm what is the fq., intensity and duration

Answer 36

fq: 3MHz
intensity: 0.5-1.0 W/cm^2
duration: 5-10min

Question 37

if thermal/nonthermal US, and depth is <5 cm what is the fq., intensity and duration

Answer 37

fq. : 1MHz
intensity: 1.5-2.0 W/cm^2
duration: 5-10min

Question 38

if you have an impairment of delayed tissue healing or pronlonged inflammation, what US would you use

Answer 38

non thermal

Question 39

non thermal duty cycle

Answer 39

20%, 50%

Question 40

laser

Answer 40

light amplification by stimulated emission of radiation

Question 41

low level lasers peak power is what

Answer 41

equal or less than 500mW

Question 42

high intensity lasers peak power is what

Answer 42

greater than 500mW

Question 43

laser physiological effects

Answer 43

improve mitochondrial fxn
promote collagen production
modulate inflammation
inhibit bacterial growth
promotes vasodilation
increase nerve conduction

Question 44

laser contraindications

Answer 44

direct eye exposure
pregnancy
malignancy
following acute injury where a hemorrhage is possible
open growth plates
over the thyroid or other endocrine gland