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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