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PT414 Biophysical Agents > Ultrasound > Flashcards

Ultrasound Flashcards

1
Q

What do we utilize ultrasound for? *Therapeutic modalities

A
  • Thermal
  • Non-thermal
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2
Q

What are the common transducer frequencies?

A
  • 1 MHz
  • 3.3 Mhz
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3
Q

What is the Reverse Piezo Electric effect?

A

The application of an electric field to a crystal causes a realignment of the internal dipole structure

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4
Q

What is an ERA?

A

Effective Radiating Area

The area of a therapeutic ultrasound head that produces useful ultrasonic energy, measured in square centimeters (cm2)

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5
Q

What is a BNR?

A

Beam Nonuniformity Ratio

  • The ratio of the average intensity of the ultrasound beam across the ERA divided by the peak intensity of the ultrasound beam
  • This is essentially the amount of error in the sound wave field
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6
Q

What is the smallest ERA multiple you should use when treating an area with ultrasound?

A

Never go below 1.5x ERA of the sound head.

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7
Q

What is the maximum area you should treat based on a given ERA?

A

Never exceed 4x ERA recommendation

It’s not that it is dangerous it just becomes highly ineffective.

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8
Q

In what structure is the velocity of the sound waves generated by Ultrasound the greatest?

A
  • Velocity is greatest in dense tissue
    • Collagen
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9
Q

When ultrasound waves pass through a tissue there is a “split” in the wave, one is called the transmitted wave, the other the refracted wave. Explain what those terms mean.

A
  • Refracted Wave - Refraction is the change in direction of a wave as it passes from one medium to another
  • Transmitted Wave - The remaining wave that continues on to the target area
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10
Q

What is the relationship between temperature and frequency?

A

Temperature increase is proportional to frequency

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11
Q

What depth does a 1MHz frequency reach?

A

5cm

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12
Q

What depth does a 3MHz frequency reach?

A

1-2cm

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13
Q

What is spatial averaged temporal peak intensity? (SATP)

A

This is what the machine reports to you as the average intensity in Watts/cm2

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14
Q

What is a duty cycle?

A

How long an ultrasound machine is on during its on/off time

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15
Q

What are the two modes for the duty cycle?

A
  1. Continuous
  2. Pulsed
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16
Q

What is needed to calculate Spatial Average Temporal Average?

A

You need the Duty cycle x SATP

So if you have a pulsed duty cycle @ 20% at an average intensity of 1.0W/cm2

20% * 1.0 = 0.2W/cm2

17
Q

What are the thermal effects of ultrasound?

A
  1. Increased metabolism
  2. Increased collagen extensibility
  3. Increased blood flow
  4. Decreased joint stiffness
  5. Decreased muscle spasms and pain
  6. Creates a mild inflammatory response as the result of mast cells
  7. Could cause a periosteal burn
18
Q

What factors affect temperature increases in ultrasound?

A
  1. Frequency
  2. Intensity
  3. Duration
  4. Area
    1. Tissue Type
    2. ERA
  5. Speed of movement
  6. Individual person
  7. Machine
19
Q

What are the contraindications for both thermal and non-thermal ultrasound?

A
  1. Implanted electronic devices
  2. Cancer
  3. Acute DVT
  4. Pregnancy
  5. CNS Tissue
  6. Eyes
  7. Male/Female reproductive organs
20
Q

What are the contraindications for thermal ultrasound?

A
  1. Acute inflammation
  2. Joint cement & plastic
  3. EPiphyseal plates
  4. Fractures
  5. Breast Implants
21
Q

What are the adverse reactions of ultrasound?

A
  1. Burns due to standing waves
  2. Cross-contamination infection
  3. Blood vessel endothelial lining damage
22
Q

A patient walks in and requests an ultrasound treatment, what are your setting considerations when setting up the ultrasound to use?

A
  1. Frequency
  2. Duty Cycle
  3. Intensity
  4. Time/Duration
  5. Positioning
23
Q

What is the general guideline for intensity settings in ultrasound when treating acute inflammation?

A

20% pulsed @0.5-0.8W/cm2

24
Q

What is the general guideline for intensity settings in ultrasound when treating subacute inflammation/proliferation?

A

0.5-1.5 W/cm2 Mild Warmth- Moderate Warmth

25
Q

What is the general guideline for intensity settings in ultrasound when treating Chronic inflammation?

A

1.0-2.0 W/cm2 Strong Heat, NO PAIN

PT414 Biophysical Agents (8 decks)

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