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