Ultrasound

Question 1

conversion

Answer 1

mechanical energy produced by sound waves absorbed by body tissues and changed to thermal energy

Question 2

transducer

Answer 2

converts electrical energy into acoustical energy via pizoelectrical effect

Question 3

transducer head sizes vary from 1-10 cm. what is the most commonly used?

Answer 3

5cm

Question 4

how do you pick a transducer size?

Answer 4

based on size of treatment area

Question 5

effective radiating area (ERA)

Answer 5

the area of the transducer from which the ultrasound radiates

Question 6

what determines the treatment depth?

Answer 6

output frequency

Question 7

1 MHz output is for _____ tissues and 3 MHz is for ________ tissues.

Answer 7

deep, superficial

Question 8

is adipose tissue transparent to ultrasound?

Answer 8

yes

Question 9

does 3 MHz or 1 MHz have more scattering of sound waves?

Answer 9

3, therefore less is available for deeper tissues

Question 10

what kind of ultrasound is applied to achieve thermal effects? what about non-thermal effects?

Answer 10

continuous
non-continuous

Question 11

T or F: ultrasound energy is uniformly distributed over the surface of the transducer

Answer 11

F: the center ishotter than the edges, this is why you have to move it around

Question 12

bean non-uniformity ratio

Answer 12

spatial peak intensity: spatial average intensity

Question 13

why do you want a low BNR?

Answer 13

more uniform energy and therefore less risk of tissue damage

Question 14

BNR should be less than ______:1

Answer 14

6

Question 15

spatial average intensity

Answer 15

total power (watts) / area of transducer head (cm^2)

Question 16

duty cycle

Answer 16

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

Question 17

a duty cycle of less than ____% is considered pulsed

Answer 17

50

Question 18

_______ ultrasound is used in subacute and chronic conditions where _______ ultrasound is better for acute stages

Answer 18

continuous
pulsed

Question 19

temporal peak intensity

Answer 19

peak intensity of ultrasound during the on time phase of the pulse period

Question 20

temporal average intensity

Answer 20

the ultrasound power averaged over one pulse period

Question 21

attenuation

Answer 21

reduction of acoustical energy as it passes through soft tissue

Question 22

what affects attenuation? (3)

Answer 22

absorption
reflection
refraction

Question 23

what tissues have increased absorption?

Answer 23

tissues with high collagen and protein
ex. bones, muscles, tendons, ligs, capsules

Question 24

thermal effects of ultrasound

Answer 24

increased tissue temp
pain threshold
collagen tissue extensibility
enzyme activity
tissue perfusion
alteration of NCV

Question 25

is cavitation an effect of thermal or non-thermal ultrasound?

Answer 25

non-thermal

Question 26

cavitation

Answer 26

alternating compression and expansion of small gas bubbles in tissue fluids caused by mechanical pressure waves

Question 27

T or F: stable cavitation results in tissue damage

Answer 27

F: but unstable cavitation does (ex. cancer treatment)

Question 28

acoustic streaming

Answer 28

movement of fluids along the boundaries of cell membranes resulting from mechanical pressure wave
* may produce cellular changes and accelerate healing

Question 29

parameters:
1 HMz
100% duty cycle
1.75 w/cm^2
how long would you need to treat?

Answer 29

about 10 minutes to increase temp by 4 degrees C

Question 30

parameters:
3MHz
100% duty cycle
1.5 w/cm^2
how long would you need to treat?

Answer 30

about 4 minutes to increase temp by 4 degrees C

Question 31

goals of ultrasound (4)

Answer 31

1 - modulate pain
2- increase tissue extensibility
3 - reduce/eliminate acute inflammation
4 - accelerate healing

Question 32

precautions of ultrasound

Answer 32

acute inflammation
epiphyseal plates
fractures
breast implants

Question 33

T or F: symptoms may increase after the initial ultrasound treatment

Answer 33

T

Question 34

contraindications of ultrasound

Answer 34

acute injuries
impaired circulation
DVT
impaired cognition
impaired sensation
thrombophlebitis
joint cement
plastic components
over cancerous tumors
over vital areas
over pacemakers
over active infection

Question 35

T or F: ultrasound treats a limited area

Answer 35

T

Question 36

treatment area should be _______ times the size of the ERA

Answer 36

2-3

Question 37

direct contact mediums

Answer 37

gel or lotion
*water based only

Question 38

indirect contact mediums

Answer 38

• water immersion (tap water, saline)
• gel or water bladder

Question 39

T or F: ultrasound energy can pass through air

Answer 39

F: this is why you need a water based coupling medium

Question 40

how fast should you move the ultrasound head?

Answer 40

SLOWLY, 4cm/sec

Question 41

your patient has a rash but you really think they could benefit from ultrasound therapy. what could you do?

Answer 41

put saran wrap on first, then put the gel on top. saran wrap transmits the energy well

Question 42

when would you use an immersion technique?

Answer 42

for irregularly shaped areas

Question 43

how do you hold the ultrasound head during immersion technique

Answer 43

about 1 inch away from body part, the water is your medium

Question 44

ultrasound treatment duration depends on (3)

Answer 44

1 - size of treatment area
2 - output intensity
3 - goals

Question 45

what sensations are expected during thermal (continuous) ultrasound? what about pulsed?

Answer 45

warmth for thermal
nothing for pulsed

Question 46

your pt is experiencing some pain during ultrasound treatment. what can you do?

Answer 46

• move the sound head faster
• use a lower duty cycle
• lower the intensity

Question 47

phonophoresis

Answer 47

use of ultrasound to drive meds through the skin into deeper tissues
ex. lidocane

Question 48

do you use continuous or pulsed ultrasound for phonophroesis

Answer 48

continuous

Question 49

ultrasound + e-stim is often used to treat (2)

Answer 49

trigger points
muscle spasms