Acoustic

Question 1

List the parameters for thermal ultrasound.

Answer 1

i) 3 OR 1 MHz (depending tissue depth)
ii) (0.8-2.0) Usually 1.0-1.5 W/cm2
iii) 5 min per 5cm2 (at least ten min to accumulate heat)
iv) 100% duty cycle
Approx 3X/week.

Question 2

List the parameters for athermal ultrasound.

Answer 2

i) 3 or 1 MHz (depending on tissue depth)
ii) 0.5-1.0 W/cm2 *start at 0.8
iii) 20%-50% duty cycle
iv) 5 min per 5cm2
Approx 5X/week for 2-3 weeks then 3X/week for 2-3 weeks.

Question 3

How deep to 1MHz and 3MHz penetrate?

Answer 3

3MHz: 1-2cm
1MHz: 3-5cm

Question 4

How is acoustic impedance measured?

Answer 4

i) Half value depth: the depth to which a tissue reduces the power to 50% its original output
ii) Penetration depth: Same as above except for 37% for some reason.
* NOTE: cold will increase acoustic impedance and therefore ice should never be applied prior to US.

Question 5

What US parameters would be used for calcific tendonitis?

Answer 5

1) 0.89MHz
ii) 2.5 W/cm2
iii) 15min
iv) 20%
5X/week for 3 weeks then 3X/week for 3 weeks.