Machine settings & dangers for TUS

Question 1

What time after occurrence is an injury classed as acute/ subacute/ chronic?

Answer 1

Acute: 0-4 days
Subacute: 5-14 days
Chronic: 15+ days

Question 2

What intensity would you use for an acute injury?

Answer 2

0.1-0.3 W/cm2

Question 3

What intensity would you use for a subacute injury?

Answer 3

0.2-0.5 w/cm2

Question 4

What intensity would you use for a chronic injury?

Answer 4

0.3-0.8 w/cm2

Question 5

What duty cycle would you use for an acute injury?

Answer 5

pulse 1:4 = duty cycle 20%

Question 6

What duty cycle would you use for a subacute injury?

Answer 6

pulse 1:2 = duty cycle 33%

Question 7

What duty cycle would you use for a chronic injury?

Answer 7

pulse 1:1 = duty cycle 50%

Question 8

What frequency would you use for superficial tissues (ie down to 2.5cm)?

Answer 8

3MHz

Question 9

What frequency would you use for deeper tissues, down to eg 4cm?

Answer 9

1MHz

Question 10

How do you calculate how long to apply TUS for?

Answer 10

(Sum of duty cycle) x size of area in number of machine heads gives you your time in minutes

Question 11

How does tissue depth affect the intensity you choose?

Answer 11

• intensity is absorbed by tissues as it travels through them
• 3Mhz is only received at about 50% of its intensity at 2cm
• 1Mhz only 50% at 4cm

Question 12

What are the main dangers with TUS?

Answer 12

1. Unstable cavitation
2. Standing waves
3. Hotspots

Question 13

What is unstable cavitation?

Answer 13

Cavitation is tiny gas bubbles forming in tissues – this can be beneficial if the gas bubbles are produced in a predictable way, producing stable cavitation, which increases the acoustic streaming effect (believed the AS effect creates a small whirlpool on the wall of the cell, which increases excitability of cell, which alters membrane permeability).

Unstable cavitation means the volume of bubbles changes rapidly. The resultant temperature and pressure changes can cause cell damage (this occurs if you hold the treatment head in one place)

Question 14

What are standing waves and hotspots?

Answer 14

Standing waves (which is when an incident wave meets its reflection coming back, and the two waves multiply each other) can create ‘hot spots’ - can leave burns or blisters on the skin

Question 15

What TUS dangers relate to your preparation?

Answer 15

1. not doing the hot/ cold test
2. not checking contraindications
3. not inputting the correct parameters
4. not having the machines calibrated at least once a year so you are confident that it is delivering what it says on the screen

Question 16

What must you NOT FORGET to do or you fail?

Answer 16

1. Sensitivity test - hot and cold for tus of sharp/ blunt for IFT
2. Check contraindications