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50 Cards in this Set

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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%
hydrostatic pressure @ head
-30 mm Hg
hydrostatic pressure @ heart
0 mm Hg
hydrostatic pressure @ feet
100 mm Hg
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