SONOGRAPHY PRINCIPLES AND INSTRUMENTATION
ARDMS SPI ACTUAL EXAM LATEST 2024/2025 QUESTIONS
AND VERIFIED CORRECT ANSWERS/ ALREADY GRADED
A++
what type of wave is a sound wave? - ANSWER longitudinal, mechanical
molecules of the medium vibrate at 90 degrees to the direction of the
traveling wave - ANSWER transverse wave
what is the range of audible sound? - ANSWER 20 Hz to 20 kHz
portion of a cycle where the molecules are pushed closer together -
ANSWER compression
portion of a cycle where the molecules spread farther apart - ANSWER
rarefaction
what are the three primary acoustic variables? - ANSWER pressure,
density, particle motion
the time it takes for one cycle to occur - ANSWER period
the number of cycles per second - ANSWER frequency
relationship between period and frequency - ANSWER inverse
the speed at which sound travels through a medium - ANSWER
propagation speed (c)
relationship between stiffness and propagation speed - ANSWER direct
"c" of soft tissue - ANSWER 1540 m/s or 1.54 mm/usec
relationship between density, compressibility & elasticity to propagation
speed - ANSWER inverse
length of a single cycle - ANSWER wavelength
,wavelength formula - ANSWER propagation speed/frequency
max or min deviation of an acoustic variable from the average value of that
variable - ANSWER amplitude
units of pressure amplitude - ANSWER pascals (Pa)
the rate at which work is performed - ANSWER power
how are power and amplitude proportioned? - ANSWER power = amplitude
squared
intensity formula - ANSWER power/area (w/cm^2)
resistance to the propagation of sound through a medium - ANSWER
impedance (z)
units for impedance - ANSWER rayls
what causes a strong reflection? - ANSWER 90 degree incidence and
strong impedance mismatch
impedance formula - ANSWER z = density (p) x propagation speed (c)
sound waves are sent into the body and the returning wave is timed to
determine the reflectors distance from the transducer - ANSWER pulse-
echo technique
most common element material - ANSWER lead zirconate titanate (PZT)
pressure is created when voltage is applied to a material and electricity is
created when pressure is applied to the material - ANSWER piezoelectric
principle
number of pulses produced in 1 second - ANSWER pulse repetition
frequency (kHz)
relationship between frequency and PRF - ANSWER none
how are depth and PRF related - ANSWER inverse
,the time from the start of one pulse to the start of the next pulse - ANSWER
pulse repetition period
relationship between PRP and PRF - ANSWER inverse
relationship between PRP and depth - ANSWER direct
time during which the sound is being transmitted - ANSWER pulse duration
pulse duration formula - ANSWER period x number of cycles
what pulse duration is preferred for diagnostic imaging - ANSWER short
how is a short pulse duration achieved? - ANSWER damping layer helps to
reduce # of cycles
% of time that sound is actually being produced - ANSWER duty factor
duty factor formula - ANSWER pulse duration / PRP
duty factor of CW - ANSWER 100%
what is an optimal DF for diagnostic imaging? - ANSWER < 1%
length of a pulse - ANSWER spatial pulse length
SPL formula - ANSWER wavelength x number of cycles
decrease in amplitude and intensity of the sound beam as it travels through
tissue - ANSWER attenuation
3 dB - ANSWER +/- 50%
conversion of sound energy into heat - ANSWER absorption
greatest contributor to attenuation in tissue - ANSWER absorption
relationship between frequency and absorption - ANSWER direct
, the rate at which sound is attenuated per unit depth - ANSWER attenuation
coefficient
AC formula - ANSWER frequency/2
total amount of sound that has been attenuated at a certain depth -
ANSWER total path attenuation
total path attenuation formula - ANSWER AC x distance
AC units - ANSWER dB/cm
total path attenuation units - ANSWER dB
average rate of attenuation in ST - ANSWER 0.5 dB/cm/MHz
when sound beam strikes a smooth surface that is larger than the
wavelength - ANSWER specular reflection
when sound beam strikes a surface that is similar in size to the wavelength
of the sound beam - ANSWER non-specular reflectors (scattering)
permits imaging of organs parenchyma - ANSWER acoustic
speckle/scattering
how are frequency and scattering related? - ANSWER directly
when sound beam strikes a surface that is smaller in size to the wavelength
of the sound beam - ANSWER rayleigh scattering
% of sound transmitted at an interface - ANSWER intensity transmission
coefficient
% of sound reflected at an interface - ANSWER intensity reflection
coefficient
criteria for refraction to occur - ANSWER oblique incidence and different c
values
law governing refraction - ANSWER snell's law
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