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PTRS 705 - PT Interventions 2 > Ultrasound and Laser Therapy > Flashcards

Flashcards in Ultrasound and Laser Therapy Deck (56)
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1

What is Ultrasound?

Sound wave with frequencies above the range of human hearing

2

Ultrasound uses:

-Diagnostic test (fetal)
-Anti-cancer treatment to eradicate cancer tumors
-Heating and healing soft tissues, reducing pain, and restoring function (therapeutic)

3

Ultrasound Variables

-Size of sound head
-Frequency
-Intensity

4

Sound Head characteristics

-Head size: 2cm2, 5 (most common), 10
-Effective Radiating Area (ERA) - size of transducer that is producing the vibration
-Crystal will be slightly smaller than circumference of surface area

5

Sound Head - Beam Non-Uniformity Ratio

-Some parts of crystal may emit more energy than others
-Move sound head at all times

6

Frequency

-Frequency and shape of the wave are directly related
-Frequency and depth of penetration are inversely related
-Measured in Hz (Hertz) = 1 cycle/sec

7

What is the Frequency for therapeutic ultrasound?

0.75-3 MHz

8

What are the high frequency sound waves created with?

Piezoelectric crystals

9

Piezoelectric effect

Transforms mechanical energy to electrical energy (cigarette lighter)

10

Crystals and materials that have piezo properties? (8)

-Quartz
-Sucrose
-Topaz
-Bone
-Tendon
-Silk
-Enamel
-Synthetic crystals

11

The more dense the tissue the ________

closer together the molecules are and faster the energy will be transmitted

12

More dense tissues absorb more energy therefore ________ the penetration

decreasing

13

Why do higher frequencies decrease penetration?

Molecules vibrate faster, requiring more energy to overcome friction

14

What type of frequency will allow for deeper penetration?

Low - due to less friction

15

What frequency treats superficial tissue?

3MHz

16

What frequency penetrates to tissues b/w 2-5cm deep?

1MHz

17

What is Attenuation?

As beam passes through tissue, loses energy

18

What is Intensity in Ultrasound?

The amount of energy contained in the ultrasound beam - in Watts

19

Example problem - Intensity: Power = 2 W and sound head is 2cm2

Intensity = 1W/cm2

20

Spatial Average Temporal Peak Intensity

Highest intensity delivered w/n the ERA during a pulse

21

Intensity - Pulsed

-Interrupted periodically
-If on for 2 ms, then off for 2ms = 50% duty cycle

22

What is Duty Cycle?

% time that it is on

23

Intensity - definition

To provide the lowest intensity of ultrasound energy at the highest frequency that will transmit the energy to a specific tissue and achieve the desired therapeutic effect

24

General Thermal Effects (6)

-Reduce muscle spasm and guarding
-Modulate perception of pain
-Increase nerve conduction velocity
-Increase blood flow
-Increase enzyme activity
-Increase extensibility of collagen fibers

25

Thermal Mechanisms - Muscle @ 3 MHz

Intensity: 0.5-1.5
Time: 5-10 minutes

26

Thermal Mechanisms - Muscle @ 1 MHz

Intensity: 1.0-2.0
Time: 5-10

27

Thermal Mechanisms - Connective Tissue @ 3 MHz

Intensity: 0.5-1.0
Time: 2-10

28

Thermal Mechanisms - Connective Tissue @ 1 MHz

Intensity: 0.5-1.5
Time: 2-10

29

Non-Thermal? Effects (4)

-Increase cell membrane permeability
-Increase histamine release
-Increase macrophage activity
-Enhance wound contraction

30

Contraindications for Ultrasound

**Do NOT go over growth plates in children