Transducers and Beams Flashcards
size of the source
Aperture
A method for reducing side lobes (lateral array elements) in some arrays. It gradually decreases the vibration of the transducer surface with distance from its center by improving the directivity.
Apodization
A collection of active elements within a transducer housing
Array
Perpendicular to scan plane
Axial
The minimum distance 2 structures are separated from front to back or anterior to posterior, and still be distinguished as separate by the ultrasound machine
Axial Resolution
width of the pulse as it travels away from the transducer
Beam
Man Made-improves bandwidth, sensitivity, resolution elements
Composite
Crystals arranged in an arc; sector shape format
Convex array
Natural materials: Quartz, Rochelle salts, tourmaline
Man-made: Lead zirconate titanate or PZT barium titanate, lead metaniobate, lead titanate
Crystal
Transducer crystals lose their piezoelectric properties if they are heated above a critical temperature
Curie point
Material bonded to the back of the active element; limits “ringing” of the crystal; shortens pulse duration and spatial pulse length, therefore improving image quality
Damping
the machine’s ability to see and differentiate small structures and represent them (anatomically) correctly on the ultrasound image
Detail resolution
continually changing focus
Dynamic focusing
piezoelectric element, active element, or crystal
Element
Slice thickness resolution
Elevational resolution
Place where the beam begins to diverge (Fraunhofer zone)
Far zone
the distance from the transducer face to the focus
Focal length