Therapeutic Ultrasound

Front 1

Beam Nonuniformity Ratio (BNR)

Back 1

Uniformity of the ultrasound output as a ratio. The lower the ratio, the more uniform the beam

Front 2

Effective Radiating Area (ERA)

Back 2

Area of sound head that produces ultrasound waves. Measured in cm2.

Front 3

1 MHz Frequency

Back 3

This parameter targets tissues up to 5 cm deep. More energy absorbed in deeper tissue.

Front 4

3 MHz Frequency

Back 4

This parameter targets tissues up to 2 cm deep. More energy absorbed in superficial tissue.

Front 5

Spatial Average Intensity

Back 5

Amount of power per unit area of the sound head's ERA. Measured in W/cm2

Front 6

Reverse piezoelectric effect

Back 6

AC flows through piezoelectric crystal, causing vibration and production of high frequency sound waves

Front 7

2-3x ERA

Back 7

Ideal treatment area size

Front 8

Near Field

Back 8

Area closest to the sound head that has a less uniform beam

Front 9

Far Field

Back 9

Area farther away from the sound head that has a more uniform beam

Front 10

Half Layer Value

Back 10

Depth at which 50% of the ultrasound energy has been absorbed by the tissues

Front 11

Rate of heating is faster for this frequency.

Back 11

3 MHz frequency heating rate

Front 12

Cavitation

Back 12

Formation of bubbles that expand and contract

Front 13

Stable Cavitation

Back 13

Regular compression and expansion of bubbles

Front 14

Unstable Cavitation

Back 14

Bubbles expand then collapse. Unwanted effect on the tissues.

Front 15

Acoustic Microstreaming

Back 15

Result of stable cavitation. Increased fluid flowing around bubbles.

Front 16

Temperature for mild heating

Back 16

1 degree Celsius

Front 17

Temperature for Moderate heating

Back 17

2-3 degrees Celsius

Front 18

Temperature for Vigorous heating

Back 18

3-5 degrees Celsius

Front 19

Appropriate temperature for treating mild inflammation and accelerating metabolic rate

Back 19

Mild heating, 1 degree C

Front 20

Appropriate temperature for decreasing muscle spasm and pain, increasing blood flow, and reducing chronic inflammation

Back 20

Moderate heating, 2-3 degrees C

Front 21

Appropriate temperature for tissue elongation and scar tissue reduction

Back 21

Vigorous heating, 3-5 degrees C

Front 22

Duration of treatment is determined by these four factors

Back 22

Size of treatment area, intensity, frequency, desired temperature increase

Front 23

Rate of heating per minute for 1 MHz and 3 MHz at .5 W/cm2

Back 23

1 MHz = .04 degrees C, 3 MHz = .3 degrees C

Front 24

Rate of heating per minute for 1 MHz and 3 MHz at 1 W/cm2

Back 24

1 MHz = .2 degrees C, 3 MHz = .6 degrees C

Front 25

Rate of heating per minute for 1 MHz and 3 MHz at 1.5 W/cm2

Back 25

1 MHz = .3 degrees C, 3 MHz = .9 degrees C

Front 26

Rate of heating per minute for 1 MHz and 3 MHz at 2 W/cm2

Back 26

1 MHz = .4 degrees C, 3 MHz = 1.4 degrees C

Front 27

Sound head should be kept this far away from tissue during water immersion treatment

Back 27

.5-1 cm away from tissue

Front 28

Ideal rate of moving sound head during treatment. How does this change with a different BNR?

Back 28

4-6 cm/second; increase for higher BNR

Front 29

Duty cycle with least amount of heating

Back 29

20% Duty Cycle

Front 30

How long is the stretching window for a tissue treated at 3.3 MHz?

Back 30

3.3 minutes

Front 31

Attenuation

Back 31

Rate of absorption of ultrasound energy; increases as frequency increases

Front 32

Non-thermal effects of ultrasound

Back 32

Increase cell membrane permeability, altered diffusion across cell membrane, increased vascular permeability, secretion of chemotactics, increase blood flow, increase fibroblasts, increase phagocytosis, reduce edema, tissue regeneration, promote collagen synthesis

Front 33

Thermal effects of ultrasound

Back 33

increase nerve conduction velocity, increase collagen extensibility, increase collagen deposition, increase blood flow, decrease spasm, increase macrophages, increase leukocyte adhesions

Front 34

Contraindications of ultrasound

Back 34

ischemic areas or impaired circulation, hemorrhage, pelvic/lumbar area during pregnancy or menstruation, cancerous tumors, over the spinal cord or a large nerve plexus, fracture or stress fracture site, active infection, anesthetized areas, around the eyes, heart, skull or genitals

Front 35

General indications of ultrasound

Back 35

joint contracture, muscle spasm, neuroma, scar tissue, trigger points, warts, spasticity in muscle, postacute decrease of myositis ossificans, inflammation (pulsed=acute, continuous=chronic)

Front 36

How long is the stretching window for a tissue treated at 1 MHz?

Back 36

5.5 minutes

Front 37

What is the best way to maximize the stretching window?

Back 37

Stretch the tissue during and immediately after the treatment.

Front 38

How many days do you usually use ultrasound before re-evaluating its effectiveness?

Back 38

10-14 days

Front 39

What happens if you apply a heat pack before a thermal ultrasound treatment and how should you change your treatment if you do this?

Back 39

The tissue heats about 2-3 minutes faster, but does not heat more overall. You should decrease the duration of your treatment about 2-3 minutes.

Front 40

When using the bladder method of ultrasound application, where do you need to apply coupling gel?

Back 40

Between the sound head and bladder, and bladder and skin.

Front 41

Why do tendons and ligaments heat faster than muscle tissue?

Back 41

They have a higher water and collagen content.

Front 42

How should you change your intensity if you decide to use the immersion method instead of the direct method of ultrasound application? Why?

Back 42

Increase the intensity about .5 W/cm2 to account for the attenuation that will occur in the water.

Front 43

Why do you want a lower duty cycle for more acute injuries?

Back 43

To decrease the total amount of energy transferred to the tissues, which also decreases the potential for thermal effects.

Front 44

What frequency and temperature would you use to treat a trigger point?

Back 44

3 MHz, because they are typically superficial and at a moderate temperature (2-3 degrees) to decrease pain and spasm

Front 45

You are applying ultrasound to an acute rectus femoris strain. What are your treatment parameters and why?

Back 45

Goal: promote healing through mechanical effects
Frequency: 1 MHz because it is a deeper tissue
Intensity: .5-1 W/cm2 because it is acute and you want less total energy in the tissues
Duty Cycle: 10% or 20% to minimize possible thermal effects
Duration: About 5 minutes (range from 3-7 min) to decrease total amount of energy into tissues

Front 46

You are applying ultrasound to a patient's elbow to treat lateral epicondylitis and address the pain and tightness in that area. The patient can tolerate an intensity of 1.5 W/cm2. What are your remaining treatment parameters and why?

Back 46

Goal: Moderate heating (2-3 degrees C)
Frequency: 3 MHz for superficial tissue
Intensity: 1.5 W/cm2 because of patient tolerance
Duty Cycle: 100%
Duration: About 3 minutes