SONOGRAPHY CANADA – CORE QUESTIOS WITH
ANSWERS
What is the I SPPA for mechanical bioeffects? - Answers-190W/cm^2
What is the I SPTA for thermal bioeffects? - Answers-720mw/cm^2
Recommended MI for fetal scanning - Answers-MI < 1.9
Recommended TI for fetal scanning - Answers-TI < 0.7
After what fetal age is safe to use PW doppler? - Answers-14 weeks
What does ALARA stand for - Answers-as low as reasonably achievable
Frequency - Answers-# of cycles/second
F = 1/p
Period - Answers-time it takes for 1 cycle to occur (usec)
P = 1/f
Wavelength - Answers-length of 1 cycle (mm)
Wavelength = c/f
Inversely proportionate to frequency
Assumed speed of sound in soft tissue - Answers-1540 m/s
1.54mm/usec
Intensity - Answers-I = power/area
Measured in Watts
Proportionate to amplitude squared
Range equation - Answers-distance to reflector = 1/2 speed of sound x GRT
Go return time (GRT) - Answers-13usec for 1cm of depth
Acoustic impedance (z) - Answers-difference between media determining % reflection
and % transmission of sound (Rayls)
Z= density x speed of sound
Z=pxc
% reflection equation - Answers-
Larger AI difference results in ___ reflection - Answers-greater
, Pulse duration (PD) - Answers-time for one pulse
Tx is ringing
PD = period x n; n = # of cycles in pulse
Pulse repetition period (PRP) - Answers-the time from the beginning of one pulse to the
beginning of the next
Time tx is ringing and listening for 1 scan line
PRP = 13usec/cm x imaging depth
Pulse repetition frequency (PRF) - Answers-# of pulses in 1 second (khz)
PRF = 1/PRP
Duty factor - Answers-% tx is ringing over tx ringing and listening
DF = (PD/PRP) x 100%
Frame time - Answers-time it takes to create a single frame (msec)
FT = PRP x lines/frame
Frame rate - Answers-# of frames per second (Hz)
FR = 1/FT
Spatial pulse length (SPL) - Answers-length of space of one pulse (mm)
SPL = wavelength x n; n = # of cycles in pulse
Is sound a transverse or longitudinal wave? - Answers-longitudinal
What kind of pressure wave is sound? - Answers-mechanical
Infrasound range - Answers-< 20Hz
Audible sound range - Answers-20Hz - 20khz
Ultrasound range - Answers->20khz
Bulk modulus - Answers-describing stiffness/intermolecular bond strength
Higher BM = more stiff
Relationship between speed of sound and BM - Answers-speed is proportionate to BM
Which has a bigger impact on velocity: BM or density? - Answers-BM
Relationship between speed of sound and density - Answers-speed is inversely
proportionate to density
Density - Answers-mass per volume
Kg/m^3
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