Chapter 2 Penny Flashcards
the diameter of the piezoelectric element(s) producing the beam
aperture
the transducer with multiple active elements
array
same as real-time ultrasound
automatic scanning
the ability to accurately identify reflectors that are arranged parallel to the ultrasound beam
axial resolution
the damping material of the transducer assembly, which reduces the number of cycles produced in a pulse
backing material
the range of frequencies present within the beam
bandwidth
occurs when in-phase waves meet; the amplitudes of the two waves are added to form one large wave
constructive interference
the ability to differentiate one shade of gray from another
contrast resolution
a synonym for the active element of the transducer, the piezoelectric part of the transducer assembly that produces sound
crystal
the temperature at which an ultrasound transducer will gain its piezoelectric properties, and also the temperature at which a transducer will lose the ability to produce sound if heated again above this temperature
curie point
the transducer commonly referred to as a curvilinear or convex probe
curved sequenced array
the process of reducing the number of cycles of each pulse in order to improve axial resolution
damping
same as backing material; the part of the transducer assembly that reduces the number of cycles produced in a pulse
damping material
the inability to determine the depth of the reflector if the pulses are sent out too fast for them to be timed
depth ambiguity
occurs when out-of-phase waves meet; the amplitude of the resultant wave is smaller than either of the original waves
destructive interference
spreading of the beam that occurs in the far zone
divergence
the piezoelectric part of the transducer assembly that produces sound
element
slice-thickness plane
elevational plane
the resolution in the third dimension of the beam
elevational resolution
the diverging part of the beam distal to the focal point
far zone
the area of the beam with the smallest beam diameter
focal point
the portion of the transducer that is in contact with the patient’s skin
footprint
three-dimensional ultrasound in real-time
4D ultrasound
one complete ultrasound image
frame
the number of frames per second
frame rate
far zone
Fraunhofer zone
the number of cycles per second
frequency
the number of cycles per second
frequency
near zone
Fresnel zone
states that waves are the resultant of the interference of many wavelets produced at the face of the transducer
Huygen’s principle
waves whose peaks and troughs overlap
in-phase
the ability to accurately identify reflectors that are arranged perpendicular to the ultrasound beam
lateral resolution
the man-made ceramic of which many transducer elements are made; abbreviated PZT
lead zirconate titanate
the transducer commonly referred to as the linear probe or transducer
linear sequenced array
the component of the transducer that is used to step down the impedance from that of the element to that of the patient’s skin
matching layer
transducer that acquires real-time volumes using up to 10,000 elements, compared to the 128-512 elements used in a standard 1D array transducer
matrix array transducer
transducers with a motor for steering the beam
mechanical scanheads
the part of the beam between the element and the focal point
near zone
the length of the region from the transducer face to the focal point
near-zone length
waves that are 180 degrees opposite of each other; the peak of one wave overlaps the trough of the other and vice versa
out-of-phase
transducer that uses phasing, or small time differences, to steer and focus the beam
phased-array
the method of focusing and/or steering the beam by applying electrical impulses to the piezoelectric elements with small times differences between shocks
phasing
the ability to convert pressure into electricity and electricity into pressure
piezoelectric