Kremkau Chapter 3 Key Terms Flashcards
Aperature
size of a transducer element or group of elements.
Apodization
nonuniform driving of elements in an array to reduce grating lobes
Array
a transducer assembly containing several piezoelectric elements
Axial
in the direction of the transducer axis
Axial Resolution
the minimum reflector separation along the sound path that is required to produce separate echoes
Beam
region containing continuous wave sound; region through which a sound pulse propagates.
Composite
combination of a piezoelectric ceramic and a nonpiezoelectric polymer
Convex Array
curved linear array
Crystal
element
Curie Point
temperature at which an element material loses its piezoelectric properties
Damping
material attached to the rear face of a transducer element to reduce pulse duration; the process of pulse duration reduction.
Detail Resolution
the ability to image fine detail and to distinguish closely spaced reflectors
Disk
a thin, flat, circular object.
Dynamic aperature
aperature that increases with increasing focal length
dynamic focusing
continuously variable reception focusing that allows the increasing depth of the transmitted pulse as it travels.
Element
the piezoelectric component of a transducer assembly
Elevational Resolution
the detail resolution in the direction perpendicular to the scan plane. it is equal to the section thickness and is the source of section thickness artifact.
Far zone
the region of a sound beam in which the beam diameter increases as the distance from the transducer increases. aka far field
Focal length
distance from a focused transducer to the center of a focal region or to the location of the spatial peak intensity
Focal region
region of minimum beam diameter and area
Focal zone
length of the focal region
Focus
the concentration of the sound beam into a smaller beam area than would exist otherwise
Grating lobes
additional weaker beams of sound traveling out in directions different from the primary beam as a result of the multi element structure of transducer arrays
Lateral
perpendicular to the direction of sound travel
Lateral Resolution
minimum reflector separation perpendicular to the sound path that is required to produce separate echoes.
Lead zirconate titanate
a ceramic piezoelectric material . PZT
Lens
a curved material that focuses a sound or light beam
Linear
adjectival form of line
Linear array
array made of rectangular elements arranged in a straight line
Linear phased array
linear array operated by applying voltage pulses to all elements, but with small time differences to direct ultrasound pulses out in various directions.
Linear sequenced array
linear array operated by applying voltage pulses to groups of elements sequentially
Matching layer
material attached to the front face of a transducer element to reduce the reflections at the transducer surface
Natural Focus
the narrowing of a sound beam that occurs with an unfocused flat transducer element.
Near zone
the region of a sound beam in which the beam diameter decreases as the distance from the transducer increases; also called near field
Operating frequency
preferred frequency of operation of a transducer
Phased array
an array that steers and focuses the beam electronically
Phased linear array
linear sequenced array with phased focusing added; linear sequenced array with phased steering of pulses to produce a parallelogram shaped display
Piezoelectricity
conversion of pressure to electric voltage
Probe
transducer assembly
Resolution
the ability to distinguish echoes in terms of space, time, or strength.
Resonance frequency
operating frequency
Scanhead
transducer assembly
Sector
a geometric figure bounded by two radii and the arc of the circle included between them
Sensitivity
ability of an imaging system to detect weak echoes.
Side lobes
weaker beams of sound traveling out from a single element in directions different from those of the primary beam.
Sound beam
the region of a medium that contains virtually all of the sound produced by a transducer.
Source
an emitter of ultrasound; transducer
Transducer
a device that converts energy from one form to another
Transducer assembly
Transducer elements with damping and matching materials assembled in a case.
ultrasound transducer
a device that converts electric energy to ultrasound energy, and vice verse
Vector array
linear sequenced array that emits pulses from different starting points and from different directions
