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Therapeutic Agents > Ultrasound > Flashcards

Ultrasound Flashcards

1
Q

What frequency is considered ultrasound?

A

> 20,000 Hz

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2
Q

What is the range of therapeutic frequency for ultrasound?

A

.7–> 3.3 MHz

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3
Q

Term for as ultrasound travels through material the intensity gradually decreases?

A

attenuation

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4
Q

US term for a crystal that converts electrical energy into sound?

A

Transducer (sound head)

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5
Q

Term for amount of acoustic energy per unit of time, expressed in Watts (W)?

A

Power

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6
Q

If a patient is treated with intensity of 1.5 W/cm2 with a 10 cm2 transducer equals what wattage of energy?

A

15 W

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7
Q

Term for the power per unit area of the sound head and is expressed in W/cm2?

A

Intensity

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8
Q

What is the limit of average intensity of therapeutic US?

A

3.0 W/cm2

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9
Q

Term for the average intensity of the US output over the area of the transducer?

A

spatial average intensity

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10
Q

Term for the peak intensity of the US output over the area of the transducer?

A

spatial peak intensity

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11
Q

Where is the spatial peak intensity the greatest on the transducer? Lowest?

A

Greatest-center of beam

lowest- edges of beam

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12
Q

Term for the ratio of the spatial peak intensity to the spatial average intensity?

A

Beam Nonuniformity Ratio (BNR)

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13
Q

What is the BNR usually between in most units?

A

between 5:1 and 6:1

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14
Q

An US machine with BNR of 5:1; intensity set at 1.0 W/cm2; the spatial peak intensity may be as high as what amount?

A

5.0 W/cm2

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15
Q

US setting where there is continuous delivery of US throughout treatment period?

A

Continuous US

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16
Q

US setting where the delivery of US is during only a portion of the treatment period?

A

pulsed US

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17
Q

Term for the proportion of the total treatment time the US is on, can be expressed as a percentage or ratio?

A

duty cycle

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18
Q

Term for the spatial average intensity of the US during the on time of the pulse?

A

spatial average temporal peak (SATP)

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19
Q

Term for the spatial average intensity of the US averaged over both the on time and the off time of the pulse?

A

spatial average temporal average (SATA)

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20
Q

Term for the number of compression-rarefaction cycles per unit of time; expressed in cycles per second (Hz)?

A

frequency

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21
Q

Term for the area of the transducer from which the US energy radiates?

A

Effective reading area (ERA)

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22
Q

The effective reading area (ERA) is always smaller than what?

A

The area of the treatment head

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23
Q

Initially, the US beam delivered from a transducer __?____ and then ___?___

A

converges and then diverges

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24
Q

What field is the convergent region?

A

near field (Fresnel zone)

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25
Q

What field is the divergent region?

A

far field (Fraunhofer zone)

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26
Q

Term for conversion of the mechanical energy of the US into heat.

A

Absorption

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27
Q

Term for the redirection of an incident beam away from a reflecting surface at a angle equal and opposite to the angle of incidence.

A

reflection

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28
Q

Term for the redirection of a wave at an interface.

A

Refraction

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29
Q

Term for a measure of the decrease in US intensity at the US wave travels through tissue

A

attenuation

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30
Q

Term for the depth of tissue at which the US intensity is half its initial intensity.

A

half -depth

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31
Q

If the US is set at a 1 MHz intensity, what is the half depth of US available? What about 3 MHz?

A

3cm, 1cm

32
Q

Term for the intensity maxima and minima at fixed positions one-half wavelength apart.

A

standing-wave

33
Q

Term for the formation, growth, and pulsation of gas or vapor filled bubbles caused by US.

A

cavitation

34
Q

What happens to the bubbles in the tissue during the compression phase of an US wave?

A

Are made smaller

35
Q

What happens to the bubbles in the tissue during the rarefaction phase of an US wave?

A

They expand

36
Q

Term for micro-scale eddying that takes place near any small, vibrating object.

A

micro-streaming

37
Q

Where does micro-streaming occur?

A

around the gas bubbles set into oscillation by cavitation

38
Q

Term fro the steady circular flow of cellular fluids induced by US.

A

acoustic streaming

39
Q

What flow is larger in scale, micro-streaming or acoustic streaming?

A

acoustic streaming

40
Q

How does acoustic streaming alter cellular activity?

A

by transporting material from one part of the US field to another

41
Q

Term for the application of US with a topical drug in order to facilitate transdermal drug delivery.

A

phonophoresis

42
Q

What does it mean when it says the crystal has piexoelectric properties?

A

they develop an electric charge on certain crystals by applying mechanical pressure to them

43
Q

How is US generated?

A

1) Applying a high-frequency alternating current to crystal in transducer (Piezoelectric properties)
2) US uses the reverse piezoelectric effect to produce sound waves from electric charges

44
Q

What are the US transducers made out of?

A

plumbium, zirconium, titanate

45
Q

What structures are well suited to using the thermal US?

A

tendons, ligaments, joint capsules, and fascia

46
Q

The effects of thermal US is dependent upon what 4 things?

A

1) tissue that the US is applied to
2) frequency
3) intensity
4) duration of US

47
Q

What is the US heating rate proportional to?

A

tissue’s absorption coefficient

48
Q

The non-thermal effects of US are attributed to what 3 things?

A

1) cavitation
2) micro-streaming
3) acoustic streaming

49
Q

What are some effects non-thermal US have?

A

1) increase intracellular Ca+2
2) increase skin and membrane permeability
3) increase mast cell degranulation
4) increase chemotactic factor
5) increase histamine release

50
Q

what sort of presentations would you consider US application?

A

1) soft tissue shortening
2) pain control
3) tendon and ligament injuries
4) dermal ulcers
5) surgical skin incisions
6) bone fractures

51
Q

What does the US do with the drug that is applied during phonophoresis?

A

US increases drug penetration by increasing the permeablility of the stratum corneum.

52
Q

when should you not use phonophoresis?

A

if patient is already receiving the drug of the same type by a different method.

53
Q

What are the 9 contraindications of US?

A

1) malignant tumor
2) pregnancy
3) CNS tissue
4) joint cement
5) plastic components
6) pacemaker
7) thrombophlebitis, hemorrhagic or ischemic areas
8) eyes
9) reproductive organs

54
Q

What are 4 precautions of US?

A

1) acute inflammation
2) epiphyseal plates
3) fractures
4) breast implants

55
Q

What are 3 adverse effects of US?

A

1) burn (most common)
2) cause damage to endothelial lining of the blood vessels
3) cross contamination of patients
* *occur when US is used incorrectly or when contraindicated

56
Q

What needs to be documented when performing US?

A

1) area of body
2) frequency
3) intensity
4) duty cycle (if not doc. 100% is assumed)
5) duration
6) immersion method (if used, state)
7) patient’s response

57
Q

What are the 12 steps when applying US?

A

1) assess patient and set goals of treatment
2) determine if US is most appropriate treatment
3) check for contraindications
4) apply transmission medium
5) select sound head with an ERA approx. 1/2 size of area treated
6) select optimal parameters
7) clean sound head
8) place sound head on area to be treated
9) turn on US machine…DUH
10) move sound head within treatment area
11) Times up, remove gel from patient and sound head; reassess
12) document

58
Q

How do you determine what frequency to set for US application?

A

according to the depth of tissue to be treated

59
Q

How do you determine your duty cycle for US application?

A
  • goal of treatment
  • -> if goal is to increase tissue temp.-100% duty cycle
  • ->if want non-thermal effects- 20% duty cycle
60
Q

What kind of US intensity would you use for acute conditions?

A

.2-.5 W/cm2–> to reduce the production of thermal effects; patient should feel no warmth

61
Q

What kind of US intensity would you used for subacute conditions?

A

.5-1.0 W/cm2–> if minimal thermal effects are desired; patient should feel no warmth or only mild warmth on skin

62
Q

What kind of US intensity would you use for chronic conditions?

A

1.0-2.0 W/cm2 –> if maximal safe thermal effects are desired, the patient should feel a strong sensation of warmth but no discomfort

63
Q

How do you determine the duration of US treatment?

A

In relation to ERA and size of the area

  • -> for most thermal or nonthermal application, US should be applied for 5-10 min for each treatment area that is twice the ERA of the transducer
  • -> duration is increased with lower intensities or frequencies are used and vice versa
64
Q

How long should you apply US to facilitate bone healing?

A

15-20mins

65
Q

What does the size of the area to be treated depend on?

A

ERA–> suggests to be about 2X the ERA; area should not exeed 4X of ERA (not effective- due to heating and cooling)

66
Q

How do you determine the number and frequency of US treatments? for thermal and non-thermal

A

thermal- applied every other day or 3X/wk
nonthermal- applied daily
**dependent upon goal of treatment and response of patient; if no positive signs after 1-3 treatments-re-evaluate

67
Q

After how many treatments should you discontinue US to reduce possible risk factor of overexposure of US?

A

12-15 treatments

68
Q

When during your treatment session should you perform US?

A

either before or after interventions

–>careful if using after ice application

69
Q

During your treatment session, if you are trying to increase tissue extensibility, when do you apply US?

A

directly before stretching or during, if possible

70
Q

How should you move the sound head over treatment area?

A

1.5’’ per second, small overlapping circles

71
Q

What are the 3 basic requirements that must be met to use direct-contact procedure, correctly?

A

1) the contour of the part being treated must allow for good contact of sound head for the duration of treatment
2) the skin or soft tissue must not be sensitive to pressure that moving the sound head along the skin causes pain
3) skin must be intact

72
Q

When is the immersion procedure indicated?

A

when the 3 criteria for direct-contact are not met or when treating small irregular surfaces; joints of hand and feet; treatment areas that are too sensitive to pressure or have broke skin

73
Q

How should the sound head be in regards to the treatment area?

A

1/2 to 1 inch away from skin and perpendicular

74
Q

Why can you not use the immersion method within a whirpool?

A

the amount of reflection that occurs and potential for increasing the intensity in certain areas near metal

75
Q

At what increments should you increase the intensity during the immersion method?

A

.5 W/cm2 due to poor transmission

76
Q

What US method is used for irregularly contoured body parts that are more proximal?

A

Fluid-filled bag or cushion procedure

Therapeutic Agents (1 decks)

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