Ch. 1 & 2 Vocab Flashcards
Sonography
medical two-dimensional, cross-sectional and three-dimensional anatomical and flow imaging using ultrasound.
Ultrasound
sound having a frequency greater than what humans can hear, that is greater than 20kHz (20,000 Hz).
Image
a reproduction, representation, or imitation of the physical form of a person or thing.
Transducer
a device that converts energy from one form to another.
Pulse-Echo Technique
ultrasound imaging in which pulses are reflected and used to produce a display.
Gray-Scale
a range of brightness between white and black.
Scan Line
a line produced on a display that represents ultrasonic echoes returning from the body.
Linear Image
an anatomical image presented in a rectangular format.
Sector Image
an anatomic image presented in a pie slice-shaped format.
Doppler Effect
is a change in frequency caused by motion of reflectors.
Color-Doppler Display
the representation of two-dimensional, real-time Doppler-shift information superimposed on a real-time, gray scale, anatomical, cross-sectional image.
Spectral-Doppler Display
the presentation of Doppler information in a quantitative form. Visual display of Doppler spectrum.
Wave
a traveling variation of one or more quantities.
Sound
a mechanical, longitudinal traveling wave in which particles in the medium move.
Acoustic Variables
sound wave variations of one or more quantities such as pressure, density, temperature or particle motion.
Vacuum Matter
the absence of matter (no matter = no sound)
Electromagnetic Waves
waves that travel at the speed of light and don’t need a medium for propagation (light, microwaves, X-Rays, TV and radio waves.)
Mechanical Waves
waves that are categorized by the direction of the displacement of individual particles in the medium, either transverse or longitudinal.
Transverse Wave
a wave in which particles in the medium vibrate perpendicular or “transverse” to the direction of the wave motion.
Longitudinal Wave
a mechanical compressional wave in which particles in the medium vibrate parallel to the direction of the wave motion.
Cycle
a completion of one compression and one rarefaction.
Compression
a region of high pressure and density in a sound wave.
Rarefaction
a region of low pressure and density in a sound wave.
Frequency
a number of cycles per second. Hz = 1 cycle/sec Freq(MHz)=PropSpeed(mm/us)/Wavelength(mm) or 1/Period(us)
Period
the time it takes for one cycle to occur (μs). Period(us)=1/Freq(MHz)
Wavelength
the length of space (distance) over which a cycle occurs (mm). Wavelength(mm)=PropSpeed(mm/us)/Freq(MHz)
Stiffness
(hardness) is the resistance of a material to compression.
Propagation Speed
the speed at which a wave moves through a medium (m/s, km/s, mm/μs). Prop Speed (mm/us)=Wavelength(mm)xFreq(MHz)
Harmonics
frequencies that are even and odd multiples of fundamental or operating frequency.