304lecture: ultrasound

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304lecture: ultrasound
2014-05-04 16:01:00
304 modalities

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  1. the human ear is capable of detecting sound waves ranging from:

    any range above this range is considered:

    what is the range of theraputic ultrasound:
    • the human ear is capable of detecting sound waves ranging from:  16-20,000 Hz
    • any range above this range is considered: ultrasound
    • theraputic ultrasound: 1,2,3 MegaHz
    • 100x the audible frequency, that is why you can not hear ultrasound
  2. ultrasound energy travels in a more ________ form instead of in all directions like audible sound waves.
    ultrasound energy travels in a more cylindrical form instead of in all directions like audible sound waves.
  3. ultrasound needs a medium in which to travel.

    which medium can U.S. not travel thru:

    what is the best medium for U.S:
    • U.S cannot pass thur air, too high of frequency
    • best medium: water (distilled).

    use more gel than you think you need, if gel drys up... U.S. is not getting to the tissues
  4. U.S travels in waves.

    list the 4 characterstics that make up a wave:
    • wavelength
    • frequency
    • amplitude (intensity)
    • velocity
  5. the sound head is called:
    a transducer
  6. cycles of compression/rarefaction per second (Hz) is called:
  7. list 3 commone frequency choices, along with which type of penetration, and the depth of penetration:
    • 1 MHz
    • deep
    • 3-5 cm

    • 2 MHz
    • intermediate
    • 1-3 cm

    • 3 MHz
    • superficial
    • 0-2 cm
    • just below adipose; collegen rich tissue absorbs from deep tissues
  8. the % of time that U.S energy is being emitted from the sound head is called:
    duty cycle
  9. the amout of power (watts) generated per unit area is called:

    what is always the lable of units for this term:
    • the amout of power (watts) generated per unit area is called:  intensity
    • lable: W/cm2
  10. the lenght of the application, determied by the output intesity and the specific goals of the tx is called:
  11. U.S. is produced when an alternating current flows thru a ____________ that is in a transducer.
    U.S. is produced when an alternating current flows thru a piezolectric crystal that is in a transducer.
  12. a crystal that produces positive and negative electrical charges when it is compressed or expanded is called:
    plumbiam zirconium titanate

    these compressions and expansions cause vibration which gets passed from the transducer into the tissues by way of a medium
  13. describe the energy formation of the following in the transducer:

    Near field:
    far field:
    • near field: high and low pressure variances
    • far field: interacting waves converge (forming a peak; peak is always moving, energy peak is labled in watts)
  14. energy transmitted parallel to the direction of sound are called:
    longitudinal waves

    • usual and desired effect
    • waves go thru compression and rarefactions (areas of expansion)
  15. energy transmitted perpendicular to the direction of sound is called:

    give an exmple:
    transverse waves

    • example: U.S wave striking bone
    • hard to controll
    • undesired waves
    • striking bone causes increased velocity - increased friction - more heat = burning!
  16. the highest intensity within the beam (the peak; spatial peak intensity) relative to the average intensity of the transduecer is called:
    beam nonuniformity ratio
  17. the lower the beam nonuniformity ratio (BNR) the _______ uniform the beam.

    what is the BNR ratio that is considered unsafe:
    • the lower the beam nonuniformity ratio (BNR) the more uniform the beam.
    • unsafe BNR ratio: greater than 8:1
    • ideal is 1:1
    • listed on the U.S head
  18. describe the clinical application of the beam nonuniformity ratio (BNR):
    if wand is not moving, peak stays in small area.... High ratio... BURNS

  19. peak intensity of U.S. beam is called:
    - expressed in:

    average intensity over area of transducer is called:
    -expressed in:
    • peak intensity of U.S. beam is called: peak intensity
    • expressed in: Watts (W)

    • average intensity over area of transducer is called: average intensity
    • expresssed in: W/cm2
    • what the machine will display
  20. the term that describes the number of waves occurring in 1 second is called:

    • the depth of penetration is inversely related to the output frequency
    • depth of penetration is tissue dependent
    • 3 MHz: less prenetration, more absorption; 3x the heat build up... Heats
    • 1 MHz: goes deep, but heats 1/3rd of the temp
  21. the maximum average during the "on" time:

    the average with "on" and "off" time:
    the maximum average during the "on" time: spatial average temporal peak

    the average with "on" and "off" time: spatial average temporal average

  22. how can you decrease the average intensity of the output, reducing the thermal effects while still allowing for the non thermal effects of US:
    pulsing the duty cycle
  23. the portion of the transducer's surface area that actually produces U.S. waves is called:
    effective radiating area (ERA)

    • listed on the machine
    • varies in size dependent on the body part (if interchangeable)
    • look at both the BNR and ERA
    • tx area is 2-3 x the ERA
    • more than 2x the ERA, not creating the physiological response intended
  24. describe the clinical application of the ERA:
    • general rule: tx area is 2x the size of the sound head
    • duration is 5-10 mins. for each tx area that is 2x the ERA
  25. describe how U.S velocity is directly related to tissue density:
    • the higher the density, the greater the velocity
    • the higher frequencies cause more molecular friction and make it more difficult to pass thru the tissues
    • heats faster
  26. how fast does U.S. travel thru soft tissue at 1 MHz:

    how fast does U.S travel thru compact bone at 1 MHz:

    what is the clinical application of these velocities in regards to periosteal pain:
    • how fast does U.S. travel thru soft tissue at 1 MHz: 1540 m/sec
    • how fast does U.S travel thru compact bone at 1 MHz: 4000 m/sec

    • clinical application of these velocities in regards to periosteal pain:
    • burning of the bone
    • most sensitive tissue to pain in the body!!
  27. the depth of penetration is  __________ to the output frequency.
    the depth of penetration is  inversely related to the output frequency.


    absorption increases as frequency increases
  28. how do tissues high in water content affect absorption:

    how do tissues high in collagen content affect absorption:

    list 3 structures high in collagen:
    • high in water content: decrease absorption
    • high in collagen content: increase absroption

    • tissues that heat fast:
    • cartilage (high in collagen)
    • ligaments (high in collagen)
    • tendon (at the end further away from the muscle; high in collagen)
  29. list 4 factors that will determine the tx duration:
    • therapeutic goal
    • size of the area being tx'ed
    • output intensity
    • frequency used
  30. the tx area should be no larger than how much the size of the surface area of the sound head:

    in general, how long is the tx time:

    in general, about how many tx's should a pts. receive over the course of the recovery
    • the tx area should be no larger than how much the size of the surface area of the sound head: 2x the surface area of the sound head
    • general tx times: 5-12 minutes (depends on desired outcomes)
    • how many tx's over course of recovery: 10-14 tx's
  31. the passage of U.S. thru the body causes the tissues to acquire________ and results in ________.

    when the U.S. beam strikes an acoustical interface, such as different tissue layers, what happens to the energy:
    the passage of U.S. thru the body causes the tissues to acquire kinetic energy and results in cellular vibration.

    what happens to the energy as it strikes different tissue layers: reflected, refracted, or absorbed
  32. the cosine law says that because the angle of incidence deviates away from 90 degrees, the efficiency of the energy affecting the tissues is decreased by the cosine of the angle
    • interface:
    • air/soft tissue: 99.9 % reflection
    • water/soft tissue: .2 % reflection
    • soft tissue/fat: 1.0 % reflection
    • soft tissue/tendon: 10-20% reflection
    • soft tissue/bone: 15-40% reflection
  33. the decrease in a wave's intensity resulting from the absorption, reflection, and refraction of the energy is called:

    what law is this:

    because of this less energy is able to pass deeper into the tissues

    law of grothus draper: any energy not reflected or absorbed is passed on to the underlying tissues
  34. why must a transmission medium be used during a U.S tx:

    what is a good medium, ideally:

    what can happen if a poor conductive medium is used:
    • to allow the waves to pass out of the transducer and into the tissues
    • ideally a good medium is: nonreflective
    • if a poor conductive medium is used: it can ruin the crystal, energy is produced but cant go anywhere
  35. list 3 applications of the coupling agents:
    • make sure you have a conductive medium
    • use caution over irregular body parts
    • don't increase intensity without the sound head in contact with the medium and the body part
  36. the method of U.S. with a gel to transfer the energy between the U.S. head and the skin is called:

    when is this method less effective:
    direct coupling

    • less effective: with irregular and hair body parts
    • use firm, constant pressure with sound head
  37. the coupling medium used to distribute the energy evenly over irregular shaped areas is the:
    water immersion technique

    • if possible , use distilled water and ceramic tub
    • operator should keep hand out of water
  38. the coupling medium that is uses a balloon or a plastic bag with water or ultrasound transmission gel is called:
    the bladder method

    • used for irregular body parts
    • rarely used
    • avoid air bubbles
  39. individual pulses cause oscillations between cells and molecules, creating gas filled bubbles called:
  40. cavitation that occurs when the bubbles compress during high pressure peaks and expand when there is low pressure is called:
    • stable cavitation
    • controlled environment
  41. cavitation that occurs after the compression phase from the high pressure bubbles that collapse on t he expansion phase is called:
    • unstable (transient) cavitation
    • intensity is too high, possible tissue damage can occur
    • implodes on itself
  42. the unidirectional flow of fluid tissue components due to stable cavitation is called:

    the flow of fluid causes which to things:

    • causes:
    • a change in cell membrane permeability to sodium and calcium ions important in the healing process
    • enhance nutrient delivery
  43. list 2 ways Pulsed U.S can aid in the non-thermal biophysical effects:
    • fibrinolysis: break up of fibrin - scar tissue
    • phagocytosis: removal of inflammatory debris
  44. list 3 ways in which Pulsed (non-thermal) U.S. at low dosage  could helps healing connective tissue to be stronger:
    • calcium uptake in fibroblasts
    • increase fibroblastic activity
    • synthesis of collagen

    angiogensis: new blood vessels, increased BF, enhanced nutrient delivery, increased cell permeability, increased phagocytosis
  45. which mode is used for thermal effects, pulsed or continueous?
  46. tissues heated at which frequency, retains heat approximately 2x as long as heat generated by another frequecny:
    tissued heated at 1 MHz retains heat approx. 2x as long as heat generated by 3 MHz

    1 MHz heats up slower (.20 C per W/cm2 per min) but penetrates deeper

    3 MHz heats up faster (.6o C per W/cm2 per min) but not as deep
  47. to acheive a therapetuci effect thru U.S heating, the tissue temp must be elevated for a minimum of how long:

    how can you enhance the heating of deep tissues prior to the tx:
    3-5 minutes

    prior to tx: pretx'ing with a moist hot pack (MHP)
  48. list the nonthermal physiological effects of U.S.: (15)
    • increased cell membrane permeability
    • altered rate of diffusion across cell membrane
    • increased vascular permeability
    • secretion of chemotactics
    • increased blood flow
    • increased fibroblastic activity
    • increased uptake of calcium
    • stimulation of phagocytosis
    • production of healthy granulation tissue
    • synthesis of protein
    • reduction of edema
    • synthesis of collagen
    • diffusion of ions
    • tissue regeneration
    • formation of stronger, more deformable connective tissue
  49. list the thermal physiological effects of U.S.: (8)
    • increased sensory nerve conduction velocity
    • increased motor nerve conduction velocity
    • increased extensibility of collagen rich structures
    • increased collagen deposition
    • increased blood flow
    • reduction of muscle spasm
    • increased macrophage activity
    • enhanced adhesion of leukocytes to damaged endothelial cells
  50. During the acute and proliferation stages of the injury response cycle, U.S. is useful for:
    increased fibroblastic activity
  51. both pulsed (acute) and continuous (contraindicated in acute inflammatory) have effects that aid in tissue healing, list (3):
    • fibroblastic activity
    • collagen synthesis
    • deposition of collagen
  52. in the acute inflammatory phase of the injury response cycle, ideally how much of a tissue temperature rise do you want to get maximum effects:
    1 degree C or less
  53. U.S. causes an increase in blood flow due to the:
    thermal effects

    O2, nutrients, waste removal
  54. continuous U.S. has been reported to increase the local blood flow for how long after the tx:
    45 minutes
  55. list to physiological effects that may also promote increased blood flow as a result of U.S.: (2)
    • altered vascular permeability
    • vasodilation
  56. ideally, how much of a TTR would you want to get maximum effects of increased blood flow:
    2-3 degree C
  57. U.S. may control pain through the direct effect by which mechanism:
    • may directly influence pain by raising the pain threshold by altering cell membrane permeability (to sodium ions)
    • gate theory of pain control
    • possible conterirritant
  58. indirect pain reduction thru U.S. results from which (2) mehcanisms:
    • effects of increased blood flow
    • effects of temperature increase will reduced muscle spasm
  59. ideally how much of a TTR would you want to achieve maximum effects in pain control:
    2-3 degree C TTR
  60. ideally how much of a TTR would you want to achieve maximum effects of tissue elasticity:
    4 degree C
  61. after U.S. the "stretching window" (draper) is short lived, how long is the window after tx:

    which one of the frequencies may have a slightly longer stretching window than the other:
    • stretching window: 3 minutes
    • 1MHz may have a slightly longer stretching window

    may want to place a stretch during the tx
  62. the application of therapeutic U.S. to assist in the diffusion of medication thru the skin is called:
  63. U.S. phonophoresis does not "drive" the medication thru the skin, rather describe the mechanism of phonophoresis:
    it opens pathways for the medication to diffuse thru the skin into deeper tissues
  64. list (3) advantages of phonophoresis:
    • med can be delivered to a larger area compared to an injection
    • noninvasive
    • avoids the liver which can lessen the effectiveness of the medication (oral meds)
  65. skin is a major factor on the success of medication diffusion (getting meds. to the appropriate tissues), describe the following factors:

    • hydration: the more water the better
    • age: skin is more dehydrated with age
    • composition: best near hair follicles, sebaceous glands, and sweat ducts
    • vascularity: high vascular areas are better, vasodilation helps as well (use heat before tx)
    • thickness: areas of thinner, less dense skin are better
  66. list the common meds commonly administered via phonophoresis:
    • cortiocosteroids: hydrocortisone and dexamethasone
    • salicylates: aspirin based (myoflex)
    • anesthetics: lidocaine

    • usually use continuous U.S. (want thermal effects although pulsed has more effect on cell membrane permeability)
    • make sure the med is good coupling agent
  67. list the indications for the use of U.S.: (11)
    • acute inflammatory conditions (pulsed output)
    • chronic inflammatory conditions (pulsed or continuous output)
    • tissue extensibility
    • joint contractures
    • scar tissue
    • muscle spasm
    • tissue healing
    • wound healing
    • trigger areas
    • post-acute reduction of myositis ossificans
    • neuroma
  68. list the contraindications of the use of U.S.: (13)
    • acute conditions (continuous output)
    • ischemic areas
    • tendency to hemorrhage (over the pelvic or lumbar area in menstruating female pts)
    • areas around the eyes, heart, skull, genitals
    • pregnancy when used over the pelvic/lumbar
    • over cancerous tumors
    • over the CNS spinal cord
    • anesthetic areas
    • over a fx site before healing is complete
    • stress fx site
    • over site of active infection
    • areas of impaired circulation
    • plastic implants
  69. describe the clinical application of the following..

    acute conditions:
    chronic conditions:
    • acute conditions: require more tx over a shorter period of time (1-2x/day for 6-8 days)
    • chronic conditions: require few tx over a longer period of time (alternating days for 10-14 days)

    limit tx to a total of 14 days
  70. what is the appropriate parameters for U.S. used to tx fx healing:
    low frequency, low intensity, pulsed US
  71. what is the proposed mechanism of U.S. use in the tx of fx healing:
    • works by providing stress (minimal) with the U.S. waves on the fx site - thus encouraging Wolff's law
    • if applied 1-2 x a day for 20 minutes, may speed up fx healing
  72. the adverse effects of U.S. are minimal if used correctly, but list (3):
    • burns: high intensity stationary application
    • standing waves: blood cell stasis collection of gas bubbles, plasma in nodes
    • -damages endothelial lining of vessels
    • cross contamination-bacterial spread from one person to the next
  73. how fast should the wand be moving at during an U.S. application:
    4 cm per second
  74. what is the deepest penetration frequency of ultrasound:
    1 MHz
  75. which biological tissues has the lowest amount of attenuation (absorbption) of ultrasound:
    adispose tissue
  76. the ultrasound head should be moved at a rate of:
    4 cm/second
  77. name two mechanical effects of ultrasound:
    microstreaming: one directional motion of fluid caused by a sound wave

    cavitation: pressure changes created by the ultrasonic wave
  78. the ratio that decscribes the peak intensity  and the average intensity is called:
    BNR (beam nonniformity ratio)
  79. the average intensity during the "on" time of the pulse is called:
    spatial average temporal peak intensity (SATP)
  80. the greatest velocity of ultrasound is achieved when passing thru which biological tissue:
  81. the relationship between absorption and penetration of ultrasound is known as:
  82. ultrasound is produced by what type of crystal:
  83. when using U.S., a transverse wave is created when the sound wave strikes which type to tissue:
  84. the law that states the intensity of the radiation striking a surface varies inversely with the square of the distance from the source is called:
    inverse square law
  85. fill in the blank:

    3 MHz, _________ %, .5 W/cm2, 7 minutes = TTR of 1.05
  86. the rate of heating for ultrasound with a parameter set to 2 MHz, 100 % for 1.5 W/cm2
    .6 per minute
  87. what is the largest possible tx area using a sound head with an ERA of 8 cm2
    16-24 cm2
  88. what is the most common frequency for shortwave diathermy:
    27.12 MHz