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Flashcards in ultrasound & shockwave Deck (83)
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1

Ultrasound frequency Is higher than sound human can hear. T or F.

- True

2

What is the ultrasound frequency?

- 20,000 cycles per second or hertz

3

What is seen at the inner end of the transducer head?

- piezoelectric head

4

AC stands for

Alternating current

5

Ultrasound is produced through ____ through ______

- Reverse piezoelectric effect
- Through application of high frequency AC to a piezoelectric crystal
- Causes mechanical change to piezoelectric crystal

6

Most commonly used piezoelectric material

- Plumbium zirconium titanate

7

All types of piezoelectric material used

- Plumbium zirconium titanate
- Quartz
- Barium titanate

8

When crystal expands

- It compresses material in front of it

9

When crystal compresses

- It rarefies the material

10

Alternating compression-rarefaction is

- Ultrasound wave

11

Outside crystal is the

- Plate

12

Fresnel zone is the

- Near field

13

Describe the fresnel zone

- Absence of divergence
- Maxima and minima are close to each other

14

Length of near field depends on

- Diameter of treatment head
- Frequency

15

Fraunhofer zone is the

- Far field

16

Describe the fraunhofer zone

- More divergent
- Nearly absent interference that gradually decreases with increasing distance to transducer
○ Decreased with increasing distance to transducer
○ Practical application: underwater technique

17

Body tissue should be in which field

- Between near and far field
- Has nicest sound wave
- Not too divergent or convergent

18

Ultrasound is attenuated in the tissue by

- Absorption, reflection, refraction

19

Attenuation

Decreasing US intensity as wave travels through tissue

20

Attenuation is greatest with

- High collagen content
High US frequencies

21

Critical angle of Ultrasound

- 15 degrees

22

Ultrasound heats tissues with

- High collagen content
- High absorption coefficient

23

What are tissues with high collagen content

- Tendons
- Ligaments
- Joint capsules
- Fascia

24

Ultrasound is ideal for muscles. T or F.

- False

25

For thermal effects, US should be in what mode?

- Continuous

26

Thermal effects of US

- Increase metabolic rate
- Reduction of pain and spasm
- Inc nerve conduction velocity
- Inc in blood flow
- Inc tissue extensibility

27

Non thermal effects is given in what mode?

- Pulsed mode

28

Non-thermal effects

- Inc cell membrane permeability
- Inc intracellular calcium ions
- Promotes macrophage responsiveness
- Inc protein synthesis by fibroblasts

29

Acoustic streaming

- Steady circular flow of cellular fluids induced by US
- Reason for US being used in phonophoresis
○ US pushes meds into body

30

Cavitation

- Formation, pulsation and growth of gas-filled bubbles
- Responsible for cell permeability
- Macrophages and fibroblasts