Week 3: Therapeutic Ultrasound

Question 1

What is ultrasound?

Answer 1

• high freq sound waves (>20,000Hz)
• causes vibration of the material it passes through

Question 2

Attenuation

Answer 2

as an ultrasound travels through material it decreases in intensity as it travels through a tissue

Question 3

high density human tissue

Answer 3

connective tissue, ligaments, fascia, bone, tendons

• faster absorption than low density

Question 4

T or F: US is transmitted poorly through air because it is low density. That is why we use aqueous gel or water to transmit waves to body tissues

Answer 4

true

Question 5

Absorption and when is it higher ?

Answer 5

• conversion of US energy into thermal energy
• depends on type of tissue and freq
• its higher in tissues with high collagen and when a high freq is used

Question 6

refracted

Answer 6

• waves passing through denser material are bent and no longer follow original path

Question 7

Reflection

Answer 7

• depends on angle of interface between tissues of differing density
• standing wave may create a “hot spot”

Question 8

Bone absorbs how much

Answer 8

96%

Question 9

Low density of human tissues

Answer 9

blood, fat, muscle

Question 10

How are sound waves produced

Answer 10

• piezoelectric crystals expands (and compresses the material in front of it) and contracts (rarefies material in front)
• only contracts and expands in the center

Question 11

Compression
vs
Rarefaction

Answer 11

Compression: areas of increased density of molecules
Rarefaction: areas of decreased density of molecules

Question 12

Beam Non-uniformity Ratio (BNR)

Answer 12

• range of intensity
• expresses variance in acoustic energy across the beam
• spatial peak intensity/spatial average intensity
  best = 1-2, avg =5

Question 13

Frequency

Answer 13

determines how deep the US will penetrate the tissue
- 1MHz - 6cm depth
- 3-3.3 MHz - 2.5 cm depth

Question 14

T or F: Frequency and depth are directly proportional

Answer 14

False, they’re inversely related

Question 15

Intensity

Answer 15

power of us energy is product of wave phase duration and wave amp
- spacial avg intensity
- power measured in watts

Question 16

Mode: US Pulsed

Answer 16

• bouts of energy on and off
• pulse on / (pulse on + off)
  Common: 20% and 50% pulsed

Question 17

treatment area for US

Answer 17

• 2x ERA (maximum 4x ERA)

Question 18

Treatment Duration & Number

Answer 18

2-3x / week for 10-15 treatments

Question 19

do you want US parallel or perpendicular to the skin surface?

Answer 19

perpendicular with soundhead in contact with the skin to minimize reflection

Question 20

Patterns for Moving sound head

Answer 20

1. parallel overlapping strokes
2. overlapping circles

Question 21

Thermal effects of US & how to make it occur more rapidly

Answer 21

• creating a deeper heat
• increase power/intensity, increase duration, higher freq, smaller tx area

Question 22

Non-thermal effects of US

Answer 22

• used to alter membrane permeability and accelerate tissue healing
• during high degree with low intensity US (pulsed)

Question 23

Cavitation

Answer 23

cycles of compression and rarefaction create gas bubbles

Question 24

Microstreaming

Answer 24

cavitation produces currents and may change cell permeability and activity

Question 25

acoustic streaming

Answer 25

forward movement of fluid by US waves

Question 26

effects and usage of Low intensity pulsed US

Answer 26

• increases bone angiogenesis
• stimulates osteogenesis
• enhances production of calcifies bone matrix
• to facilitate healing of fractures/repair tendon-bone junctions

Question 27

Can you use US to deliver a topical drug?

Answer 27

Yes!! Its called phonophoresis

• antiinflammatory
• nsaids
• analgesics

Question 28

Contraindications to THERMAL US

Answer 28

• PREGNANCY (over low back/abdomen)
• over malignancy
• over active epiphyseal bone growth
• TB infection
• Hemorrhagic conditions
• Impaired circulation

Question 29

Contraindications to PULSED US

Answer 29

• PREGNANCY (over low back/abdomen)
• over malignancy
• hemorrhagic conditions

Question 30

What to look at to assess if US is effective?

Answer 30

• look at pain, TTP, resisted motion tenderness, ROM,
• Documentation

Question 31

US is good for what types of pain?

Answer 31

• Myofascial pain!!
• back pain has conflicting evidence
  and shoulder pain has no evidence

Question 32

US is good for what type of inflammatory condition?

Answer 32

• carpal tunnel syndrome & calcified tendonitis
• little evidence for lateral epicondylitis