Ultrasound Transducers Flashcards
The widening of the sound beam in the far field
angle of divergence
size of the transducer elements
aperture
nonuniform driving (excitation) of the elements in an array to reduce grating lobes
apodization
collection of active elements connected to individual electronic currents in one transducer assembly
array
ability to distinguish two structures along a path parallel to the sound beam
axial resolution
multiple transducer elements with individual wiring and system electronics
channels
occurs when two waves in phase with each other create a new wave with amplitude greater than the original two waves: in phase
constructive interference
curved linear transducer containing multiple pizoelectric elements
convex array
pizoelectric element
crystal
temp to which a material is raised, while in the presence of a strong electrical field, to yield piezoelectric properties.
curie point
material attached to the rear of the transducer element to reduce the pulse duration
damping
occurs when two waves out of phase with each other create a new wave with amplitude less than the two original waves: out of phase
destructive interference
includes both axial and lateral resolution
detail resolution
deviation in the direction of the sound eave that is not a result of reflection, scattering, or refraction
diffraction
aperture that increases as the focal length increases; minimizes change in the width of the sound beam
dynamic aperture
variable receiving focus that follows the changing position of the pulse as it propagates through tissue; the electrical output of the elements can be tined to “listen” in a particular direction and depth
dynamic focusing
piezoelectric component of the transducer
element
detail resolution located perpendicular to the scan plane; it is equal to the section thickness and is the source of the section thickness artifact
elevation resolution
region of the sound beam in which the diameter increases as the distance from the transducer increases
far zone
distance from a focused transducer to the center of the focal zone; distance from a focused transducer to the spatial peak intensity
focal length
concentration of the sound beam into a smaller area
focal point
area or region of the focus
focal zone
fraunhofer zone
far zone
fresnel zone
near zone
additional weak beams emitted from a multi-element transducer that propagates in directions different from the primary beam
grating lobes
all points on a wave front or at a source are point of sources for the production of spherical secondary wavelets
huygens principle
interference occurring when two waves interact or overlap, resulting in the creation of a new wave
interference phenomenon
ability to distinguish two structures lying perpendicular to the sound beam
lateral resolution
a ceramic piezoelectric material
lead zirconate titanate (PZT)
material attached to the front face of the transducer element to reduce reflections at the transducer surface
matching layer
region of the beam between the transducer and focal point, which decreases in size as it approaches the focus
near zone
natural frequency of the transducer; it is determined by the propagation speed and thickness of the element in pulse ultrasound and by the electrical frequency in continuous wave
operating frequency
conversion of pressure to electric voltage
piezoelectricity
applying voltage pulses to all elements in the assembly group, but with minor time differences.
phased
operating frequency
resonance frequency
operated by applying voltage pulses to a group of elements in succession
sequenced array
additional weak beams traveling from a single element transducer in directions different from primary beam
side lobes
dividing each element into small pieces to reduce grating lobes
subdicing
device that converts energy from one form to another
transducer
transducer element, damping, matching layer, and housing; also known as probe, scan head
transducer assembly
