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50 Cards in this Set
- Front
- Back
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Typical frequency range of ultrasound is
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2MHz - 10MHz
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Audible sound frequency range is
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20Hz - 20kHz
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What is the wavelength of a 1MHz wave
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1.54mm
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Infrasound frequency range is
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< 20Hz
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Ultrasound frequency range is
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> 20kHz
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Typical period range is
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.1 - .5 microseconds
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Typical amplitude ranges are
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1MPa - 3MPa
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US power ranges from
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4-90mW
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Intensity values range from
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.01-300 W/cm**2
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Wavelength values range from
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.15-.8mm
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Typical propagation speeds range from
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500m/s - 4000m/s
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Average speed of sound in soft tissue is
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154,400 cm/s
OR 1540m/s OR 1.54mm/microsec (about 1 mile per second) |
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Typical duty factor ranges for pulsed US are
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.002-.005
or .2% - .5% |
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No significant biological effects for exposure temp
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< or = 2 degrees above normal
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Thickness of matching layer is
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1/4 of wavelength
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thickness of PZT
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.2-1 mm
or 1/2 wavelength of sound in the PZT |
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width of an element
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1/4 to 1/2 of the sound's wavelength
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# PZT elements in an array transducer
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120-250 rectangular shaped
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# gray shades a human eye can detect
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20
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time for an odd or even field to be written on a tv screen
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1/60 sec
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time for a frame to be written on a tv screen
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1/60(odd) + 1/60(even) = 1/30 sec
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typical amplification value
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60-100 dB
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number of gray shades expressed in bits
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2^# bits
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speed of sound in most PZT materials
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4-6 mm/microseconds
or 4 times greater than the speed of sound in soft tissue |
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RBCs resonate between a frquency of
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2-4 MHz
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% RBCs in blood
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45%
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hydrostatic pressure @ head
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-30 mm Hg
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hydrostatic pressure @ heart
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0 mm Hg
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hydrostatic pressure @ feet
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100 mm Hg
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cos 0 degrees
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1
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cos 60 degrees
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1/2
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cos 90 degrees
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0
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range of frequencies of a Doppler shift
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20 Hz - 20 kHz
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Sonographic pulses are typically ? cycles
AND Doppler pulses are typically ? cycles |
Sonographic 2-3
Doppler 5 - 30 |
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typical pulse duration
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.3-2 microseconds
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typical SPL
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.1-1 mm
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typical PRP
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.1-1 ms
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typical PRF
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1-10kHz
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no significant biological effects for exposures up to ? hours
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50
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Threshold of fetal temperature for induction of fetal anomolies is
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41 degrees centigrade (105.8 degrees Fahr)
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No significant biological effects for unfocused beam intensity below
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100 mW/cm**2
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No significant biological effects for focused beam intensity below
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1 w/cm**2
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No biological effects noticed for ? time period for an unfocused beam
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>1 sec and < 500 sec
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No biological effects noticed for ? time period for an focused beam
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> 1 sec and < 50 seconds
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No biological effects noted for intensity X exposure time < ?
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50 joules/cm**2
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transient cavitation occurs at pressures exceeding
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10MPa
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Typical atttenuation in soft tissue
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.5dB/cm-Hz
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What are dynamic ranges for:
transducer receiver scan converter display archive |
transducer 120 dB
receiver 100-120 dB scan converter 40-50 display 20-30 archive 10-30 |
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Reynolds number
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(AvgVel X vessel diam X density)/poise
poise=viscosity |
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Reynolds value which predicts turbulent flow
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>2000
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