210 Chapter 10: Glossary
Glossary
MMode Motion Mode showing the phasic motions of the cardiac structures. A
single beam of ultrasound is transmitted and reflected signals are
displayed as dots of varying intensities, which create lines across the
screen.
mechanical index
(MI)
An indication of the likelihood of mechanical bioeffects occurring: the
higher the MI, the greater the likelihood of mechanical bioeffects. See
Chapter 6, “Safety” for a more complete description of MI.
MI/TI See mechanical index and thermal index.
NTSC National Television Standards Committee. A video format setting. See
also PAL.
PAL Phase Alternating Line. A video format setting. See also NTSC.
pulsed wave (PW)
Doppler mode
A Doppler recording of blood flow velocities in a range specific area
along the length of the beam.
skinline A depth on the display that corresponds to the skin/transducer
interface.
thermal index (TI) The ratio of total acoustic power to the acoustic power required to raise
tissue temperature by 1°C under defined assumptions. See Chapter 6,
“Safety” for a more complete description of TI.
TIB (bone thermal
index)
A thermal index for applications in which the ultrasound beam passes
through soft tissue and a focal region is in the immediate vicinity of
bone.
TIC (cranial bone
thermal index)
A thermal index for applications in which the ultrasound beam passes
through bone near the beam entrance into the body.
TIS (soft tissue
thermal index)
A thermal index related to soft tissues.
Tissue Harmonic
Imaging
Transmits at one frequency and receives at a higher harmonic
frequency to reduce noise and clutter and improve resolution.
transducer A device that transforms one form of energy into another form of
energy. Ultrasound transducers contain piezoelectric elements, which
when excited electrically, emit acoustic energy. When the acoustic
energy is transmitted into the body, it travels until it encounters an
interface, or change in tissue properties. At the interface, an echo is
formed that returns to the transducer, where this acoustic energy is
transformed into electrical energy, processed, and displayed as
anatomical information.
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