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PMod > Ultrasound > Flashcards

Ultrasound Flashcards

1
Q

is sound with a frequency greater than 20,000 cycles
per second (Hz) that, when applied to the body, has thermal and non-thermal effects

A

Ultrasound

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2
Q

Generation of Ultrasound

A

by applying a high frequency AC to a piezoelectric crystal.

piezoelectric material expands and contracts in response to AC

— Plumbium zirconium titanate (PZT), quartz, barium titanate
— When the crystal expands, it compresses the material in front of it;
when it contracts, it rarefies the material.

— the alternating compression-rarefaction is the ultrasound
wave

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3
Q

Ultrasound enters the body and is attenuated in the tissue by

A

absorption, reflection and refraction (critical angle: 15°)

— Attenuation
— decreasing US intensity as the wave travels through tissue
— greatest in tissues with high collagen content and with the
use of high US frequencies.

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4
Q

Fresnel zone

A

-near field
-absence of divergence
-maxima and minima are close
-length of near field depends on diameter frequency

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5
Q

Fraunhofer Zone

A

-far field
-more diverse
-Ideal: near part of the far field
-Practical: underwater technique

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6
Q

Microscopic movement or oscillation of body fluids and tissues induced by US

A

Micromassage

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7
Q

The steady, circular flow of cellular fluids induced by US

A

Acoustic Streamin

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8
Q

The formation, growth and pulsation of gas-filled bubbles by US

A

Cavitation

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9
Q

(high absorption coefficients)

A

Heats tissues with high collagen content

tendons, ligaments, joint capsules , and fasciae.
not ideal for muscles (has a relatively low absorption
coefficient)

Generally heats smaller, deeper areas compared to superficial heating agents

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10
Q

Thermal Effect of US

A

-Cont mode
- Inc metabolic Rate
- Induction of pain and spasm
-Inc nerve conduction velocity
-Inc bloodflow
-Inc soft tissue extensibility

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11
Q

Nonthermal effects of US

A

-Pulsed mode
-inc cell membrane permeability
-inc intracellular calcium ions
-Promotes macrophages responsiveness
-inc rate of protein synthesis by fibroblast

-Acoustic streaming
-Micromassage
-Cavitation

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12
Q

Continuous US Indication

A

— Before stretching shortened soft tissues
— Due to immobility, inactivity or scarring
— Reduction of pain

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13
Q

Pulsed US Indication

A

To accelerate tissue healing
— Dermal ulcers, surgical skin incisions, tendon injuries and
bone fractures
— Phonophoresis
— Transdermal drug delivery

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14
Q

US Application Parameters

US can be described by its

A

— Frequency (MHz)
— Intensity (W/cm2)
— Beam non-uniformity ratio (BNR)
— Duty cycle (%)
— Treatment duration (mins)
— Effective radiating area (ERA) – (cm2)

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15
Q

Depth of penetration is lower in

A

3 MHz

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16
Q

Maximum temperature achieved is higher

A

3 MHz

17
Q

3 MHz Depth of penetration

A

1-2 cm deep

18
Q

1 MHz depth of penetration

A

up to 5 cm deep

19
Q

percentage or ratio of the pulse duration to the pulse period

A

Duty cycle

20
Q

Thermal duty cycle

A

100% (continuous) duty cycle

21
Q

Nonthermal duty cycle

A

Usually 20% duty cycle

22
Q

used to determine
intensity when thermal US is applied.

A

Patient’s report of warmth

23
Q

If BNR is 6 : 1, when the spatial average intensity is ___, the spatial peak intensity could be as high as __

A

1.5 W/cm2, 9 W/cm2

24
Q

The ratio of spatial peak intensity to the spatial average
intensity

A

Beam non-uniformity ratio (BNR)

25
Q

US Intensity

Soft tissue

A

0.5 – 1.0 W/cm2 when 3 MHz is used for 5-10 mins

1.5 – 2.5 W/cm2 when 1 MHz is used for 5-10 mins

— Stretching is recommended to be applied during heating and maintained for 5-10 mins after US.

26
Q

US Intensity

Painful Areas

A

0.5 – 3.o W/cm2, 1 or 3 MHz for 3-10 mins

27
Q

US Intensity

Wound Healing

A

0.5 – 1.0 W/cm2, 3 MHz, 20% duty cycle for 3-10 mins

Around wound perimeter or using coupling sheet over
the wound or using underwater technique

28
Q

US Intensity

Tendon and Ligament Repair

A

— Acute: 0.5 – 1.0 W/cm2
–1 or 3 MHz, pulsed mode
–To accelerate tissue healing

— Chronic: high enough intensity to increase tissue temperature,
continuous mode
–To address tissue shortening

29
Q

US Intensity

Bone Fracture

A

Very-low-dose US
— 0.15 W/cm2, 1.5 MHz, 20% duty cycle for 15 – 20 mins

30
Q

US Intensity

Carpal Tunnel Syndrome

A

0.5 - 1.0 W/cm2
, 1 MHz, pulsed 1:4 for 5 – 15 mins

31
Q

US Intensity

Phonophoresis

A

0.5 – 0.1 W/cm2, 3 MHz, 20% duty cycle for 5 – 10 mins

32
Q

— Usually 5 – 10 mins for each treatment that is 2X the
Effective Radiating Area (ERA)

A

Area 20 cm2, ERA of 10 cm2 = 5-10 mins
— Area 40 cm2, ERA of 10 cm2 = 10-20 mins

33
Q

Duration is generally increased when

A

— lower intensities or lower frequencies are used.
— areas larger than twice ERA
— heating effects are desired

34
Q

US Method of Application

A

— Direct method
— Moving versus stationary method
— Glove or balloon technique
— Underwater treatment

35
Q

US Contraindications

A
  1. Malignant tumor
  2. Pregnancy
  3. CNS tissue
  4. Joint cement or plastic components of arthroplasty
  5. Pacemaker
  6. Thrombophlebitis
  7. Eyes
  8. Reproductive organs
36
Q

US Precautions

A
  1. Acute inflammation
  2. Epiphyseal plates
  3. Fractures
  4. Breast implants

PMod (10 decks)

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