US

Question 1

What is Ultrasound?

Answer 1

Form of mechanical energy consisting of high frequency vibrations >20,000 Hz.

Question 2

What happens if you increase the frequency on US?

Answer 2

The higher the frequency , the higher the rate of US absorption (faster heating ) therefore the less depth of penetration

Question 3

How does the US work?

Answer 3

works on reverse piezoelectric effect, the electrical energy (AC current) is applied to lead zirconate titanate crystal in sound head which is converted to mechanical energy.

Question 4

What are the US parameters?

Answer 4

Intensity, Frequency, Duty Cycle, Effective radiating area (ERA)-cm^2, and Beam non- uniformity ration (BNR)

Question 5

Which are some characteristics of the beam?

Answer 5

The beam may be absorbed (in tissues), reflected or refracted.

Question 6

When does reflection occur?

Answer 6

Reflection is less if the sound energy is delivered perpendicular to treatment surface or interface

Question 7

When does Refraction occur?

Answer 7

Occurs as the beam travels from one medium to the another (sound waves changing direction while still penetrating into deeper tissues)

Question 8

What is the Spatial Peak?

Answer 8

The highest amplitude in the beam (the sound waves penetrating into the tissues)

Question 9

What is the Spatial Average?

Answer 9

the average amplitude of the beam

Question 10

What is the BNR?

Answer 10

The ratio of the highest intensity in the field (spatial peak) to the average intensity indicated on the machine ( spatial average) - its determined by the material used for piexoelectric inducer, Most machines have ratios between 3:1 and 8:1, we want the lowest ratio

Question 11

What is the Attenuation coefficient?

Answer 11

Attenuation is the decrease in energy due to absorption, reflection, and refraction. (absorption accounts for 1/2 of attenuation.

Question 12

Tissues with more attenuation will show a ____ temperature rise.

Answer 12

Greater

Question 13

Attenuation values are higher for tissues with a ______ collagen content.

Answer 13

Higher

Question 14

Attenuation increases as _______ of US increases.

Answer 14

Frequency

Question 15

Attenuation coefficient is ______ related to penetration.

Answer 15

Inversely

Question 16

What are the mechanical effects of US?

Answer 16

• Cavitation, micro-streaming, acoustic streaming
• Increased intracellular calcium
• Promotes cell function

Question 17

How does US promote cell function?

Answer 17

• Mast cell degranulation and histamine
• Increased macrophage responsiveness
• Synthesis in Fibroblasts
• Proteoglycan synthesis in chondrocytes
• Fracture healing= some evidence for promotion of fracture healing

Question 18

What are some of the thermal effects associated with TTR? 1 deg C

Answer 18

Increases metabolism and healing (roughly 13% increase in metabolism for every 1 deg C raise- or up to 2-3 fold increase for 10 deg C rise

Question 19

What are some of the thermal effects associated with TTR? 2-3 Deg C

Answer 19

Decreases pain and muscle spasm

Question 20

What are some of the thermal effects associated with TTR? 4 deg C or greater

Answer 20

Increases extensibility of collagen and scars, and decreases joint stiffness, a 40-45 degree centigrade temperature is required for at least 5 mins

Question 21

What is duty cycle?

Answer 21

Time on: time on+ time off; reduced thermal effects as the time off allows heat to dissipate during pulsed US at lower freq.

Question 22

What is continuous sound waves (thermal)?

Answer 22

100% Duty cycle; both thermal and mechanical effects

Question 23

What is Pulsed Sound Waves?

Answer 23

anything <100%

Question 24

What % duty cycles do most machines allow?

Answer 24

20% and 50%

Question 25

What happens during 20% duty cycle?

Answer 25

Mechanical effects only

Question 26

What happens during 50% duty cycle?

Answer 26

some thermal effects, but doesn't have much use clinically

Question 27

When should you use a 1 MHz frequency?

Answer 27

tissues up to 5 cm deep

Question 28

When should you use a 3 MHz frequency?

Answer 28

tissues 1-2 cm deep

Question 29

What is intensity?

Answer 29

How much energy you are wanting to put into the tisuses

Question 30

With 1 MHz what intensity should you use?

Answer 30

1.5 to 2.0 W/cm^2

Question 31

With 3 MHZ what intensity should you use?

Answer 31

0.5 W/cm^2

Question 32

What intensity should you use if there is non- thermal effects desired?

Answer 32

Intensities of about 0.5 to 1.0 W/cm^2 have been shown to be beneficial

Question 33

What speed should you use the transducer head at?

Answer 33

Slow circles, move the head about 1 cm/sec, every circle overlaps last one by 1/2

Question 34

What should the size of the treatment area be?

Answer 34

Area covered should be about 2-3 times the size of the ERA in 5-10 mins

Question 35

When should you see the improvement with US?

Answer 35

should be detectable within 2-3 treatments, sometimes longer for more chronic problems

Question 36

What are the indications for US?

Answer 36

* Soft tissue shortening * Pain control * Dermal Ulcers * Tendon and Ligament injuries * Resorption of calcium deposits * Bone fractures * carpal tunnel syndrome * Phonophoresis * Patient Values- talk to PT about past experiences

Question 37

What are the contraindications for US?

Answer 37

* Malignancy * Pregnancy * CNS tissues * joint cement * Plastic * Pacemaker * Thrombophlebitis * Eyes and reproductive organs

Question 38

What are the Precautions with US?

Answer 38

* Acute inflammation * Epiphyseal plates * Fractures * Breast Implants