Ultrasound Flashcards

1
Q

What is the purpose of ultrasound?

A

it is a deep heating modality that can elevate tissue temperatures to depths up to five cm

can also provide some nonthermal effects

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2
Q

What are the indications for ultrasound use?

A
  • calcium deposits
  • chronic inflammation
  • delayed soft tissue healing
  • dermal ulcers
  • joint contracture
  • muscle spasm
  • trigger points
  • pain
  • warts or scar tissue
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3
Q

What are the contraindications for ultrasound use?

A
  • areas of active bleeding
  • areas of decreased temp sensation
  • areas w/ decreased circulation
  • DVT
  • infection, malignancy, or thrombophlebitis
  • over breast implants
  • over carotid sinus or cervical ganglia
  • over epiphyseal areas in young children
  • over a pacemaker
  • over pregnant women’s bellies or pelvic areas
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4
Q

What are the thermal effects of ultrasound?

A
  • acceleration of metabolic rate
  • modulation of pain
  • reduction of muscle spasm
  • decreased joint stiffness
  • alteration of nerve conduction velocity
  • increased circulation
  • increased soft tissue extensibility

All effects are dependent on the intensity, duration, and frequency selected

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5
Q

What are the nonthermal effects of ultrasound?

A
  • increased cell and skin membrane permeability
  • increased intracellular calcium levels,
  • facilitation of tissue repair
  • promotion of normal cell function
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6
Q

What is needed to eliminate as much air as possible between the ultrasound head and the target area of affect?

A

a coupling agent

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7
Q

What are the two types of coupling agents?

A

Direct (gel, lotion, etc.)

Indirect (water immersion, bladder, etc.)

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8
Q

How far should the head of the ultrasound unit be from the skin if using water immersion indrect coupling?

A

.5-3 cm away

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9
Q

How fast should you move the transducer when performing ultrasound over an area?

A

approx. 4cm per second

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10
Q

What is the spatial-average intensity?

What is the spatial-peak intensity?

What is the beam non-uniformity ratio?

A

spatial-average intensity is the intensity of the ultrasound beam averaged over the area of the transducer

spatial-peak intensity is the intensity of the ultrasound beam at it’s highest point

the BNR is the ratio between the spatial-peak and the spatial-average intensities

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11
Q

Which is preferred, a high or a low beam non-uniformity ratio?

What should the BNR value be for ultrasound?

If an Ultrasound unit does have a high BNR how should the modality technique change?

A

Low because patients will be less likely to experience hot spots and discomfort during treatment

should range between 2:1 and 8:1

make sure you are moving the transducer at a good fast pace to avoid undesirable effects such as pain caused by periosteal irritation

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12
Q

What is ultrasound frequency a determinant of?

A

the depth of US penetration

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13
Q

What is attenuation?

Which structures have a high attenuation? Low attenuation?

A

attenuation is the term that describes the inevitable decrease in energy intensity as the US travels through various tissues

tissues with high attenuation are those that are more dense and high in protein such as bone

Tissues with low attenuation are those that have a high water content such as blood plasma

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14
Q

What frequency should be used for deep structures (up to 5 cm)?

What should be used for more shallow structures (1-2 cm)?

A

1Mhz

3Mhz

this is because higher frequency means it is absorbed faster so in order to reach deep structures the beam needs to take longer to be absorbed

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15
Q

What is a duty cycle for ultrasound?

A

the ratio of when the ultrasound is on and when it is off (if it is on for 1 msec and off for 4 msec the duty cycle would be 20%)

this is used for pulsed ultrasound

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16
Q

What is the preferred duty cycle for getting the non-thermal effects from pulsed ultrasound?

A

20% or less

17
Q

What is the maximum area that should be used during an ultrasound session in clinical practice?

A

4x larger than the transducer head’s effective radiation area

18
Q

How fast should a positive response from ultrasound be observed?

How many sessions is too many?

A

within 3 sessions, if it takes longer than this than you should change the parameters or discontinue treatment

research shows that more than 14 sessions can lower WBC and RBC counts

19
Q

What is phonophoresis?

A

the use of ultrasound for the transdermal delivery of medications such an analgesics and anti-inflammatory agents