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31 Cards in this Set
- Front
- Back
This refers to location or space. A beam does not have the same intensity at different locations within the beam
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Spatial
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This refers to the maximum value
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Peak
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This refers to the median value
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Average
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This refers to all time (both transmit and receive). A pulsed beam does not have the same intensity at different times
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Temporal
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This refers only to the transmit time (pulse duration), not the listening time
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Pulsed
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Various methods of evaluating ultrasound beam intensity are especially important in the study of ___
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Bioeffects
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The intensity of a sound beam varies depending on the location of the ___
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Measurement
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Beam's intensity at the location in space where it is maximum
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Spatial Peak Intensity
I(sp) |
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Beam's average intensity across its entire cross-sectional area
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Spatial Average Intensity
I(sa) |
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Beam's intensity at the instant in time of its maximal value
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Temporal Peak Intensity
I(tp) |
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Beam's average intensity during the most intense half-cycle
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I(max) or I(m)
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Beam's average intensity during the transmit time (pulse duration) only
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Pulse Average Intensity
I(pa) |
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Beam's average intensity during the entire pulse repitition period (both transmit and receive)
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Temporal Average Intensity
I(ta) |
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Which temporal intensity is highest?
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Temporal Peak Intensity
I(tp) |
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Which temporal intensity is lowest?
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Temporal Average Intensity since it is the only intensity that includes receive/listening time
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List Temporal Intensities from largest to smallest
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I(tp) > I(max) > I(pa) > I(ta)
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To study bioeffects the intensity characteristics of sound must be described accurately with regard to both ___ & ___
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time & space
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This is measured where intensity is maximum and at the instant in time that the most powerful part of the pulse passes
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I(sptp)
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This is measured where intensity is maximum averaged over the transmit time (pulse duration)
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I(sppa)
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This is measured where intensity is maximum and averaged over time (both transmit & receive)
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I(spta)
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This is measured over the entire cross-sectional area of the sound beam and over all time
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I(sata)
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All intensities have units of ___
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W/cm(2)
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Name the 6 methods of measuring and reporting intensities
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SPTP SPTA SPPA
SATP SATA SAPA |
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Which intensity is the most relevant with respect to tissue heating?
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SPTA
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What number describes the spread of a beam in space and is unitless with a value >= 1?
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Beam Uniformity Coefficient (aka SP/SA Factor)
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What describes the relationship of beam intensities with time and is a unitless number with a value between 0 and 1?
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Duty Factor
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Describe the relationship between pulse average and temporal average intensities for continuous wave ultrasound
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They are always the same
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When pulsed and continuous wave beams have the same SPTP/SPTA intensities which beam has the higher SPTA/SATA intensity (respectively)?
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Continuous wave
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List intensities from largest to smallest
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SPTP > I(max) > SPPA > SPTA > SATA
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Of all intensity measurements, which will have the highest value?
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SPTP
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Of all intensity measurements, which will have the lowest value?
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SATA
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