Term
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Definition
Generally a beam's power ÷ its area
Can be reported in several different ways |
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Definition
Refers to distance or space
Extra note: an ultrasound beam does not have the same intensity at different locations |
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Term
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Definition
Refers to distance or space
Extra note: an ultrasound beam does not have the same intensity at different locations |
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Term
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Definition
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Term
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Definition
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Term
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Definition
Referring to all time to transmit (pulse duration) and to receive
A pulsed ultrasound beam does not have the same intensity at different times during the pulse (on and off) |
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Definition
Refers to transmission time (pulse duration)
The average intensity for the pulse duration only |
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Term
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Definition
How to report the intensity of a beam with regard to its spatial distribution
Spatial peak intensity Isp
Spatial average intensity Isa |
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Term
| Spatial Peak Intensity (Isp) |
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Definition
| The location of maximum intensity within a beam |
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Term
| Spatial Average Intensity (Isa) |
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Definition
| Average intensity in the cross-sectional area of the beam |
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Term
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Definition
How to account for a beam's intensity with regard to its pulsed characteristics
Temporal peak intensity Itp (highest)
Imax or Im
Pulse average intensity Ipa
Temporal average intensity Ita (lowest) |
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Term
| Temporal Peak Intensity (Itp) |
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Definition
| Measures the beam's intensity at the moment it has reached its maximal value |
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Term
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Definition
| The average measurement of the most intense half cycle in the pulse |
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Term
| Pulse Average Intensity (Ipa) |
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Definition
| The average intensity of the pulse duration (transmission only) |
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Term
| Temporal Average Intensity (Ita) |
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Definition
| The average of the entire pulse repetition period, so including transmit and receive times |
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Term
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Definition
Spatial peak, Temporal peak
Measured at the location where intensity is max and at the instant in time when the most powerful part of the pulse passes |
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Term
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Definition
Spatial peak, Pulse average
Measured at teh location where intensity is max, averaged over the transmit time (PD) |
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Term
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Definition
Spatial peak, Temporal average
Measured at the location where intensity is max and averaged over all time (transmit and receive) |
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Term
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Definition
Spatial average, Temporal average
Measured over the entire cross-sectional area of the sound beam and over all time |
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Term
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Definition
| Spatial average, Temporal peak |
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Term
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Definition
| Spatial average, Pulse average |
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Term
10 Commandments of Intensity
#1 - Reporting |
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Definition
| Intensities may be reported in various ways with respect to time and space |
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Term
10 Commandments of Intensity
#2 - Bioeffects |
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Definition
The different measurements of intensities are important in the study of bioeffects
SPTA intensity is most relevant with respect to tissue heating |
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Term
10 Commandments of Intensity
#3 - Units |
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Definition
| All intensities have units of watts/cm2 |
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Term
10 Commandments of Intensity
#4 - Greatest and Least Values |
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Definition
| Because peak measurements are larger than average measurements, SPTP intensity has the highest value and SATA has the lowest value |
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Term
10 Commandments of Intensity
#5 - Beam Uniformity Coefficient |
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Definition
The beam uniformity coefficient (aka SP/SA factor) describes the spread of the beam in space
Unit-less and has a value ≥ 1 |
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Term
10 Commandments of Intensity
#6 - Duty Factor |
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Definition
The duty factor describes the relationship of beam intensities with time
Unit-less and has a value 0-1 |
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Term
10 Commandments of Intensity
#7 - Continuous Wave |
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Definition
For continuous wave ultrasound, the beam is always "on"
Pulse average and temporal average intensities are the same
SPTA = SPPA and SATA = SAPA |
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Term
10 Commandments of Intensity
#8 - Pulsed vs Continuous Waves |
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Definition
When pulsed and continuous wave sound beams have the same SPTP intensities, the continuous wave beam has the higher SPTA intensity
When pulsed and continuous wave sound beams have the same SATP intensity, the continuous wave beam has the higher SATA intensity |
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Term
10 Commandments of Intensity
#9 - Temporal Considerations |
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Definition
Temporal peak intensity is the max in time
Max intensity is averaged over the most intense time
Pulse average intensity is averaged only during the pulse duration
Temporal average intensity is averaged during the PRP (on and off time) |
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Term
10 Commandments of Intensity
#10 - Spatial Considerations |
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Definition
Spatial peak intensity is the max in space
Spatial average intensity is averaged over the cross-sectional area of the beam |
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