DMS 111 - Quiz 1 & 2 Terms

sonography

medical, 2D, cross sectional & 3D anatomical & flow imaging using ultrasound

ultrasound

sound with a frequency greater than what humans can hear (more than 20KHz or 20,000 Hz)

Image

reproduction, representation, or imitation of the physical form of a person or a thing

Linear image

anatomic image presented in a rectangular formaat

transducer

device that converts energy from one form to another

pulse-echo technique

ultrasound imaging when pulses are reflected to produce a display

gray-scale

range of brightness between white and black

scan line

line produced on a display that represents ultrasonic echoes returning from the body

sector image

anatomic image presented in a pie slice shaped format

Doppler effect

change in frequency caused by motion of reflectors

color Doppler display

representation of 2D, real time Doppler-shift information superimposed on a real-time, gray scale, anatomical cross-sectional image

Spectral doppler display

presentation of Doppler info in a quantitative form. Visual display of Doppler spectrum

Pulse echo technique

Ultrasound technique using repeated cycles of ultrasound separated in time by gaps of no ultrasound to create a diagnostic image

wave

traveling variation in one or more quantities called wave variables

acoustic variable

quantiites that vary in a sound wave - pressure, density, particle motion, temperature

vacuum matter

absence of matter

electromagnetic waves

waves that travel at the speed of light and don’t need a medium for propagation

mechanical waves

waves that are categorized by direction of the displacement of individual particles in medium; can be 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

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

region of high pressure & density in a sound wave

rarefaction

region of low pressure & density in a sound wave

frequency

number of cycles per second

frequency formula

f = 1 / T (period)

period

time it takes for one cycle to occur

wavelength

length of space over which a cycle occurs

wavelength formula

wavelength = prop. speed / f

stiffness

resistance of a material to compression

propagation speed

speed at which wave moves through a medium

harmonics

frequencies that are even or odd and multiples of fundamental or operating frequency

pulse

a few cycles of ultrasound separated by gaps of no ultrasound

pulse duration

time for one pulse to occur

pulse duration formula

pd = # cycles / frequency

pulse repitition frequency

number of pulses occuring in 1s

PRF formula

PRF = 1 / PRP

pulse repetition period

time from beginning of one pulse to the beginning of the next

duty factor

fraction of time (or %) that pulsed ultrasound is on

duty factor formula

DF % = ( PD / PRP ) x 100

Spatial pulse length

length of space a pulse takes up